[wasm][asm.js] Add flag to optionally suppress asm.js messages.

src/asmjs/asm-js.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/asmjs/asm-js.h"
 
 #include "src/api-natives.h"
 #include "src/api.h"
 #include "src/asmjs/asm-typer.h"
 #include "src/asmjs/asm-wasm-builder.h"
@@ skipping 152 matching lines @@
 
 MaybeHandle<FixedArray> AsmJs::CompileAsmViaWasm(CompilationInfo* info) {
   ErrorThrower thrower(info->isolate(), "Asm.js -> WebAssembly conversion");
   base::ElapsedTimer asm_wasm_timer;
   asm_wasm_timer.Start();
   wasm::AsmWasmBuilder builder(info);
   Handle<FixedArray> foreign_globals;
   auto asm_wasm_result = builder.Run(&foreign_globals);
   if (!asm_wasm_result.success) {
     DCHECK(!info->isolate()->has_pending_exception());
-    MessageHandler::ReportMessage(info->isolate(),
-                                  builder.typer()->message_location(),
-                                  builder.typer()->error_message());
+    if (!FLAG_suppress_asm_messages) {
+      MessageHandler::ReportMessage(info->isolate(),
+                                    builder.typer()->message_location(),
+                                    builder.typer()->error_message());
+    }
     return MaybeHandle<FixedArray>();
   }
   double asm_wasm_time = asm_wasm_timer.Elapsed().InMillisecondsF();
 
   wasm::ZoneBuffer* module = asm_wasm_result.module_bytes;
   wasm::ZoneBuffer* asm_offsets = asm_wasm_result.asm_offset_table;
   Vector<const byte> asm_offsets_vec(asm_offsets->begin(),
                                      static_cast<int>(asm_offsets->size()));
 
   base::ElapsedTimer compile_timer;
@@ skipping 33 matching lines @@
   } else {
     length = base::OS::SNPrintF(text, arraysize(text), "success");
   }
   DCHECK_NE(-1, length);
   USE(length);
   Handle<String> stext(info->isolate()->factory()->InternalizeUtf8String(text));
   Handle<JSMessageObject> message = MessageHandler::MakeMessageObject(
       info->isolate(), MessageTemplate::kAsmJsCompiled, &location, stext,
       Handle<JSArray>::null());
   message->set_error_level(v8::Isolate::kMessageInfo);
-  MessageHandler::ReportMessage(info->isolate(), &location, message);
+  if (!FLAG_suppress_asm_messages) {
+    MessageHandler::ReportMessage(info->isolate(), &location, message);
+  }
 
   return result;
 }
 
 bool AsmJs::IsStdlibValid(i::Isolate* isolate, Handle<FixedArray> wasm_data,
                           Handle<JSReceiver> stdlib) {
   i::Handle<i::FixedArray> uses(
       i::FixedArray::cast(wasm_data->get(kWasmDataUsesArray)));
   for (int i = 0; i < uses->length(); ++i) {
     if (!IsStdlibMemberValid(isolate, stdlib,
@@ skipping 97 matching lines @@
       isolate, MessageTemplate::kAsmJsInstantiated, &location, stext,
       Handle<JSArray>::null());
   message->set_error_level(v8::Isolate::kMessageInfo);
   MessageHandler::ReportMessage(isolate, &location, message);
 
   return module_object;
 }
 
 }  // namespace internal
 }  // namespace v8