[foozzie] Fix mock variables that leaked into the global object

Also tidy some JS style in the file.

BUG=chromium:673246
NOTRY=true

Review-Url: https://codereview.chromium.org/2650353004
Cr-Commit-Position: refs/heads/master@{#42659}

tools/foozzie/v8_mock.js

@@ -12,57 +12,55 @@
 // This will be overridden in the test cases. The override can be minimized.
 var __PrettyPrint = function __PrettyPrint(msg) { print(msg); };
 
-
-// All calls to f.arguments are replaced by f.mock_arguments by an external
-// script.
-Object.prototype.mock_arguments = ['x', 'y']
-
-
 // Mock Math.random.
-var __magic_index_for_mocked_random = 0
-Math.random = function(){
-  __magic_index_for_mocked_random = (__magic_index_for_mocked_random + 1) % 10
-  return __magic_index_for_mocked_random / 10.0;
-}
-
+(function () {
+  var index = 0
+  Math.random = function() {
+    index = (index + 1) % 10;
+    return index / 10.0;
+  }
+})();
 
 // Mock Date.
-var __magic_index_for_mocked_date = 0
-var __magic_mocked_date = 1477662728696
-__magic_mocked_date_now = function(){
-  __magic_index_for_mocked_date = (__magic_index_for_mocked_date + 1) % 10
-  __magic_mocked_date = __magic_mocked_date + __magic_index_for_mocked_date + 1
-  return __magic_mocked_date
-}
+(function () {
+  var index = 0
+  var mockDate = 1477662728696
+  var mockDateNow = function() {
+    index = (index + 1) % 10
+    mockDate = mockDate + index + 1
+    return mockDate
+  }
 
-var __original_date = Date;
-__magic_mock_date_handler = {
-  construct: function(target, args, newTarget) {
-    if (args.length > 0) {
-      return new (Function.prototype.bind.apply(__original_date, [null].concat(args)));
-    } else {
-      return new __original_date(__magic_mocked_date_now());
-    }
-  },
-  get: function(target, property, receiver) {
-    if (property == "now") {
-      return __magic_mocked_date_now;
-    }
-  },
-}
+  var origDate = Date;
+  var handler = {
+    construct: function(target, args, newTarget) {
+      if (args.length > 0) {
+        return new (
+            Function.prototype.bind.apply(origDate, [null].concat(args)));
+      } else {
+        return new origDate(mockDateNow());
+      }
+    },
+    get: function(target, property, receiver) {
+      if (property == "now") {
+        return mockDateNow;
+      }
+    },
+  }
 
-Date = new Proxy(Date, __magic_mock_date_handler);
+  Date = new Proxy(Date, handler);
+})();
 
 // Mock stack traces.
 Error.prepareStackTrace = function (error, structuredStackTrace) {
   return "";
-}
+};
 
 // Mock buffer access in float typed arrays because of varying NaN patterns.
 // Note, for now we just use noop forwarding proxies, because they already
 // turn off optimizations.
 function __MockTypedArray(arrayType) {
-  array_creation_handler = {
+  var array_creation_handler = {
     construct: function(target, args) {
       return new Proxy(new arrayType(args), {});
     },
@@ -74,23 +72,25 @@ Float32Array = __MockTypedArray(Float32Array);
 Float64Array = __MockTypedArray(Float64Array);
 
 // Mock Worker.
-var __magic_index_for_mocked_worker = 0
-// TODO(machenbach): Randomize this for each test case, but keep stable during
-// comparison. Also data and random above.
-var __magic_mocked_worker_messages = [
-  undefined, 0, -1, "", "foo", 42, [], {}, [0], {"x": 0}
-]
-Worker = function(code){
-  try {
-    __PrettyPrint(eval(code));
-  } catch(e) {
-    __PrettyPrint(e);
-  }
-  this.getMessage = function(){
-    __magic_index_for_mocked_worker = (__magic_index_for_mocked_worker + 1) % 10
-    return __magic_mocked_worker_messages[__magic_index_for_mocked_worker];
-  }
-  this.postMessage = function(msg){
-    __PrettyPrint(msg);
-  }
-}
+(function () {
+  var index = 0;
+  // TODO(machenbach): Randomize this for each test case, but keep stable
+  // during comparison. Also data and random above.
+  var workerMessages = [
+    undefined, 0, -1, "", "foo", 42, [], {}, [0], {"x": 0}
+  ];
+  Worker = function(code){
+    try {
+      __PrettyPrint(eval(code));
+    } catch(e) {
+      __PrettyPrint(e);
+    }
+    this.getMessage = function(){
+      index = (index + 1) % 10;
+      return workerMessages[index];
+    }
+    this.postMessage = function(msg){
+      __PrettyPrint(msg);
+    }
+  };
+})();