Remove support for Javascript warnings in the VM.

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2013, 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/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1216 matching lines @@
 // Note: RBX must be preserved.
 // Attempt a quick Smi operation for known operations ('kind'). The ICData
 // must have been primed with a Smi/Smi check that will be used for counting
 // the invocations.
 static void EmitFastSmiOp(Assembler* assembler,
                           Token::Kind kind,
                           intptr_t num_args,
                           Label* not_smi_or_overflow,
                           bool should_update_result_range) {
   __ Comment("Fast Smi op");
-  if (FLAG_throw_on_javascript_int_overflow) {
-    // The overflow check is more complex than implemented below.
-    return;
-  }
   ASSERT(num_args == 2);
   __ movq(RCX, Address(RSP, + 1 * kWordSize));  // Right
   __ movq(RAX, Address(RSP, + 2 * kWordSize));  // Left.
   __ movq(R13, RCX);
   __ orq(R13, RAX);
   __ testq(R13, Immediate(kSmiTagMask));
   __ j(NOT_ZERO, not_smi_or_overflow);
   switch (kind) {
     case Token::kADD: {
       __ addq(RAX, RCX);
@@ skipping 932 matching lines @@
   __ Bind(&miss);
   __ LoadIsolate(RAX);
   __ movq(CODE_REG, Address(RAX, Isolate::ic_miss_code_offset()));
   __ movq(RCX, FieldAddress(CODE_REG, Code::entry_point_offset()));
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64