Remove support for Javascript warnings in the VM.

runtime/vm/precompiler.cc

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/precompiler.h"
 
 #include "vm/assembler.h"
 #include "vm/ast_printer.h"
 #include "vm/branch_optimizer.h"
 #include "vm/cha.h"
@@ skipping 330 matching lines @@
     { "dart:core", "NullThrownError", "NullThrownError." },
     { "dart:core", "OutOfMemoryError", "OutOfMemoryError." },
     { "dart:core", "RangeError", "RangeError." },
     { "dart:core", "RangeError", "RangeError.range" },
     { "dart:core", "StackOverflowError", "StackOverflowError." },
     { "dart:core", "UnsupportedError", "UnsupportedError." },
     { "dart:core", "_AssertionError", "_AssertionError._create" },
     { "dart:core", "_CastError", "_CastError._create" },
     { "dart:core", "_InternalError", "_InternalError." },
     { "dart:core", "_InvocationMirror", "_allocateInvocationMirror" },
-    { "dart:core", "_JavascriptCompatibilityError",
-                   "_JavascriptCompatibilityError." },
-    { "dart:core", "_JavascriptIntegerOverflowError",
-                   "_JavascriptIntegerOverflowError." },
     { "dart:core", "_TypeError", "_TypeError._create" },
     { "dart:isolate", "IsolateSpawnException", "IsolateSpawnException." },
     { "dart:isolate", "::", "_getIsolateScheduleImmediateClosure" },
     { "dart:isolate", "::", "_setupHooks" },
     { "dart:isolate", "::", "_startMainIsolate" },
     { "dart:isolate", "_RawReceivePortImpl", "_handleMessage" },
     { "dart:isolate", "_RawReceivePortImpl", "_lookupHandler" },
     { "dart:isolate", "_SendPortImpl", "send" },
     { "dart:typed_data", "ByteData", "ByteData." },
     { "dart:typed_data", "ByteData", "ByteData._view" },
@@ skipping 1867 matching lines @@
       CompilationPipeline::New(thread->zone(), function);
 
   ASSERT(FLAG_precompilation);
   const bool optimized = function.IsOptimizable();  // False for natives.
   return PrecompileFunctionHelper(pipeline, function, optimized);
 }
 
 #endif  // DART_PRECOMPILER
 
 }  // namespace dart