Reland "[wasm] Fix page size constant + test limits on max pages."

This is a reland of 183bc643.

Original change's description:
> [wasm] Fix page size constant + test limits on max pages.
> 
> BUG=chromium:801604
> R=bbudge@chromium.org,titzer@chromium.org
> 
> Change-Id: I5fa57d5f8ea288d7aef7d466cbf11df46c4dcd1d
> Reviewed-on: https://chromium-review.googlesource.com/869468
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Bill Budge <bbudge@chromium.org>
> Commit-Queue: Brad Nelson <bradnelson@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50665}

Bug: chromium:801604
Change-Id: I89943644f5921f8635e62af82bb472c7bfd5e145
Reviewed-on: https://chromium-review.googlesource.com/874696Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50707}

src/wasm/wasm-js.cc

@@ -827,7 +827,7 @@ void WebAssemblyMemoryGrow(const v8::FunctionCallbackInfo<v8::Value>& args) {
     return;
   }
   uint32_t old_size =
-      old_buffer->byte_length()->Number() / i::wasm::kSpecMaxWasmMemoryPages;
+      old_buffer->byte_length()->Number() / i::wasm::kWasmPageSize;
   int64_t new_size64 = old_size + delta_size;
   if (delta_size < 0 || max_size64 < new_size64 || new_size64 < old_size) {
     thrower.RangeError(new_size64 < old_size ? "trying to shrink memory"

test/mjsunit/wasm/memory-size.js

@@ -7,8 +7,11 @@
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
+var kV8MaxWasmMemoryPages = 32767;  // ~ 2 GiB
+var kSpecMaxWasmMemoryPages = 65536;  // 4 GiB
+
 (function testMemorySizeZero() {
-  print("testMemorySizeZero()");
+  print(arguments.callee.name);
   var builder = new WasmModuleBuilder();
   builder.addMemory(0, 0, false);
   builder.addFunction("memory_size", kSig_i_v)
@@ -19,7 +22,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
 })();
 
 (function testMemorySizeNonZero() {
-  print("testMemorySizeNonZero()");
+  print(arguments.callee.name);
   var builder = new WasmModuleBuilder();
   var size = 11;
   builder.addMemory(size, size, false);
@@ -29,3 +32,42 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   var module = builder.instantiate();
   assertEquals(size, module.exports.memory_size());
 })();
+
+(function testMemorySizeSpecMaxOk() {
+  print(arguments.callee.name);
+  var builder = new WasmModuleBuilder();
+  builder.addMemory(1, kSpecMaxWasmMemoryPages, true);
+  builder.addFunction("memory_size", kSig_i_v)
+         .addBody([kExprMemorySize, kMemoryZero])
+         .exportFunc();
+  var module = builder.instantiate();
+  assertEquals(1, module.exports.memory_size());
+})();
+
+(function testMemorySizeV8MaxPlus1Throws() {
+  print(arguments.callee.name);
+  var builder = new WasmModuleBuilder();
+  builder.addMemory(kV8MaxWasmMemoryPages + 1,
+                    kV8MaxWasmMemoryPages + 1, false);
+  builder.addFunction("memory_size", kSig_i_v)
+         .addBody([kExprMemorySize, kMemoryZero])
+         .exportFunc();
+  assertThrows(() => builder.instantiate());
+})();
+
+(function testMemorySpecMaxOk() {
+  print(arguments.callee.name);
+  var builder = new WasmModuleBuilder();
+  builder.addMemory(1, kSpecMaxWasmMemoryPages, false);
+  builder.addFunction("memory_size", kSig_i_v)
+         .addBody([kExprMemorySize, kMemoryZero])
+    .exportFunc();
+  var module = builder.instantiate();
+  assertEquals(1, module.exports.memory_size());
+})();
+
+(function testMemoryInitialMaxPlus1Throws() {
+  print(arguments.callee.name);
+  assertThrows(() => new WebAssembly.Memory(
+      {initial: kV8WasmMaxMemoryPages + 1}));
+})();