[wasm] Async-ify wasm-stepping test

This increases readability of the wasm-stepping test significantly.
Drive-by: Use more 'let' instead of 'var'.

R=yangguo@chromium.org

Change-Id: If80ba3a4b92cd3ab1c994e17fb8f40f5526517da
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1789298Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63616}

test/inspector/debugger/wasm-stepping.js

@@ -6,9 +6,9 @@ let {session, contextGroup, Protocol} = InspectorTest.start('Tests stepping thro
 
 utils.load('test/mjsunit/wasm/wasm-module-builder.js');
 
-var builder = new WasmModuleBuilder();
+let builder = new WasmModuleBuilder();
 
-var func_a_idx =
+let func_a_idx =
     builder.addFunction('wasm_A', kSig_v_v).addBody([kExprNop, kExprNop]).index;
 
 // wasm_B calls wasm_A <param0> times.
@@ -30,26 +30,26 @@ builder.addFunction('wasm_B', kSig_v_i)
     ])
     .exportAs('main');
 
-var module_bytes = builder.toArray();
+let module_bytes = builder.toArray();
 
 function instantiate(bytes) {
-  var buffer = new ArrayBuffer(bytes.length);
-  var view = new Uint8Array(buffer);
-  for (var i = 0; i < bytes.length; ++i) {
+  let buffer = new ArrayBuffer(bytes.length);
+  let view = new Uint8Array(buffer);
+  for (let i = 0; i < bytes.length; ++i) {
     view[i] = bytes[i] | 0;
   }
 
-  var module = new WebAssembly.Module(buffer);
+  let module = new WebAssembly.Module(buffer);
   // Set global variable.
   instance = new WebAssembly.Instance(module);
 }
 
-var evalWithUrl = (code, url) => Protocol.Runtime.evaluate(
+let evalWithUrl = (code, url) => Protocol.Runtime.evaluate(
     {'expression': code + '\n//# sourceURL=v8://test/' + url});
 
 Protocol.Debugger.onPaused(handlePaused);
-var wasm_B_scriptId;
-var step_actions = [
+let wasm_B_scriptId;
+let step_actions = [
   'stepInto',  // == stepOver, to call instruction
   'stepInto',  // into call to wasm_A
   'stepOver',  // over first nop
@@ -69,38 +69,33 @@ var step_actions = [
   // then just resume.
   'resume'
 ];
-for (var action of step_actions) {
+for (let action of step_actions) {
   InspectorTest.logProtocolCommandCalls('Debugger.' + action)
 }
-var sources = {};
-var urls = {};
-var afterTwoSourcesCallback;
-
-Protocol.Debugger.enable()
-    .then(() => InspectorTest.log('Installing code an global variable.'))
-    .then(
-        () => evalWithUrl('var instance;\n' + instantiate.toString(), 'setup'))
-    .then(() => InspectorTest.log('Calling instantiate function.'))
-    .then(
-        () =>
-            (evalWithUrl(
-                 'instantiate(' + JSON.stringify(module_bytes) + ')',
-                 'callInstantiate'),
-             0))
-    .then(waitForTwoWasmScripts)
-    .then(
-        () => InspectorTest.log(
-            'Setting breakpoint on line 7 (on the setlocal before the call), url ' +
-            urls[wasm_B_scriptId]))
-    .then(
-        () => Protocol.Debugger.setBreakpoint(
-            {'location': {'scriptId': wasm_B_scriptId, 'lineNumber': 7}}))
-    .then(printFailure)
-    .then(msg => InspectorTest.logMessage(msg.result.actualLocation))
-    .then(() => evalWithUrl('instance.exports.main(4)', 'runWasm'))
-    .then(() => InspectorTest.log('exports.main returned!'))
-    .then(() => InspectorTest.log('Finished!'))
-    .then(InspectorTest.completeTest);
+let sources = {};
+let urls = {};
+let afterTwoSourcesCallback;
+
+(async function Test() {
+  await Protocol.Debugger.enable();
+  InspectorTest.log('Installing code an global variable.');
+  await evalWithUrl('var instance;\n' + instantiate.toString(), 'setup');
+  InspectorTest.log('Calling instantiate function.');
+  evalWithUrl(
+      'instantiate(' + JSON.stringify(module_bytes) + ')', 'callInstantiate');
+  await waitForTwoWasmScripts();
+  InspectorTest.log(
+      'Setting breakpoint on line 7 (on the setlocal before the call), url ' +
+      urls[wasm_B_scriptId]);
+  let msg = await Protocol.Debugger.setBreakpoint(
+      {'location': {'scriptId': wasm_B_scriptId, 'lineNumber': 7}});
+  printFailure(msg);
+  InspectorTest.logMessage(msg.result.actualLocation);
+  await evalWithUrl('instance.exports.main(4)', 'runWasm');
+  InspectorTest.log('exports.main returned!');
+  InspectorTest.log('Finished!');
+  InspectorTest.completeTest();
+})();
 
 function printFailure(message) {
   if (!message.result) {
@@ -109,41 +104,37 @@ function printFailure(message) {
   return message;
 }
 
-function waitForTwoWasmScripts() {
-  var num = 0;
+async function waitForTwoWasmScripts() {
+  let num = 0;
   InspectorTest.log('Waiting for two wasm scripts to be parsed.');
-  var promise = new Promise(fulfill => gotBothSources = fulfill);
-  function waitForMore() {
-    if (num == 2) return promise;
-    Protocol.Debugger.onceScriptParsed()
-        .then(handleNewScript)
-        .then(waitForMore);
+  let source_promises = [];
+  async function getWasmSource(scriptId) {
+    let msg = await Protocol.Debugger.getScriptSource({scriptId: scriptId});
+    printFailure(msg);
+    InspectorTest.log(msg.result.scriptSource);
+    sources[scriptId] = msg.result.scriptSource;
   }
-  function handleNewScript(msg) {
-    var url = msg.params.url;
+  while (num < 2) {
+    let msg = await Protocol.Debugger.onceScriptParsed();
+    let url = msg.params.url;
     if (!url.startsWith('wasm://')) {
       InspectorTest.log('Ignoring script with url ' + url);
-      return;
+      continue;
     }
     num += 1;
-    var scriptId = msg.params.scriptId;
+    let scriptId = msg.params.scriptId;
     urls[scriptId] = url;
     InspectorTest.log('Got wasm script: ' + url);
     if (url.substr(-2) == '-1') wasm_B_scriptId = scriptId;
     InspectorTest.log('Requesting source for ' + url + '...');
-    Protocol.Debugger.getScriptSource({scriptId: scriptId})
-        .then(printFailure)
-        .then(msg => sources[scriptId] = msg.result.scriptSource)
-        .then(InspectorTest.log)
-        .then(() => Object.keys(sources).length == 2 ? gotBothSources() : 0);
+    source_promises.push(getWasmSource(scriptId));
   }
-  waitForMore();
-  return promise;
+  await Promise.all(source_promises);
 }
 
 function printPauseLocation(scriptId, lineNr, columnNr) {
-  var lines = sources[scriptId].split('\n');
-  var line = '<illegal line number>';
+  let lines = sources[scriptId].split('\n');
+  let line = '<illegal line number>';
   if (lineNr < lines.length) {
     line = lines[lineNr];
     if (columnNr < line.length) {
@@ -157,7 +148,7 @@ function printPauseLocation(scriptId, lineNr, columnNr) {
 
 async function getValueString(value) {
   if (value.type == 'object') {
-    var msg = await Protocol.Runtime.callFunctionOn({
+    let msg = await Protocol.Runtime.callFunctionOn({
       objectId: value.objectId,
       functionDeclaration: 'function () { return JSON.stringify(this); }'
     });
@@ -169,24 +160,24 @@ async function getValueString(value) {
 
 async function dumpProperties(message) {
   printFailure(message);
-  for (var value of message.result.result) {
-    var value_str = await getValueString(value.value);
+  for (let value of message.result.result) {
+    let value_str = await getValueString(value.value);
     InspectorTest.log('   ' + value.name + ': ' + value_str);
   }
 }
 
 async function dumpScopeChainsOnPause(message) {
-  for (var frame of message.params.callFrames) {
-    var functionName = frame.functionName || '(anonymous)';
-    var lineNumber = frame.location ? frame.location.lineNumber : frame.lineNumber;
-    var columnNumber = frame.location ? frame.location.columnNumber : frame.columnNumber;
+  for (let frame of message.params.callFrames) {
+    let functionName = frame.functionName || '(anonymous)';
+    let lineNumber = frame.location ? frame.location.lineNumber : frame.lineNumber;
+    let columnNumber = frame.location ? frame.location.columnNumber : frame.columnNumber;
     InspectorTest.log(`at ${functionName} (${lineNumber}:${columnNumber}):`);
-    for (var scope of frame.scopeChain) {
+    for (let scope of frame.scopeChain) {
       InspectorTest.logObject(' - scope (' + scope.type + '):');
       if (scope.type == 'global') {
         InspectorTest.logObject('   -- skipped');
       } else {
-        var properties = await Protocol.Runtime.getProperties(
+        let properties = await Protocol.Runtime.getProperties(
             {'objectId': scope.object.objectId});
         await dumpProperties(properties);
       }
@@ -194,9 +185,10 @@ async function dumpScopeChainsOnPause(message) {
   }
 }
 
-function handlePaused(msg) {
-  var loc = msg.params.callFrames[0].location;
+async function handlePaused(msg) {
+  let loc = msg.params.callFrames[0].location;
   printPauseLocation(loc.scriptId, loc.lineNumber, loc.columnNumber);
-  dumpScopeChainsOnPause(msg)
-      .then(Protocol.Debugger[step_actions.shift() || 'resume']);
+  await dumpScopeChainsOnPause(msg);
+  let action = step_actions.shift() || 'resume';
+  await Protocol.Debugger[action]();
 }