Add read only handles for the following predefined symbols

vm/stub_code_x64.cc

 // Copyright (c) 2012, 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/assembler_macros.h"
 #include "vm/compiler.h"
@@ skipping 2052 matching lines @@
   __ ret();
 
   __ Bind(&not_smi);
   __ LoadClassId(RAX, RAX);
   __ SmiTag(RAX);
   __ ret();
 
   __ Bind(&update_ic_data);
 
   // RCX: ICData
-  const String& equal_name = String::ZoneHandle(Symbols::New("=="));
   __ movq(RAX, Address(RSP, 1 * kWordSize));
   __ movq(R13, Address(RSP, 2 * kWordSize));
   AssemblerMacros::EnterStubFrame(assembler);
   __ pushq(R13);  // arg 0
   __ pushq(RAX);  // arg 1
-  __ PushObject(equal_name);  // Target's name.
+  __ PushObject(Symbols::EqualOperatorHandle());  // Target's name.
   __ pushq(RBX);  // ICData
   __ CallRuntime(kUpdateICDataTwoArgsRuntimeEntry);
   __ Drop(4);
   __ LeaveFrame();
 
   __ jmp(&compute_result, Assembler::kNearJump);
 }
 
 // Calls to the runtime to optimize the given function.
 // RDX: function to be reoptimized.
@@ skipping 81 matching lines @@
   __ cmpq(left, right);
   __ Bind(&done);
   __ popq(right);
   __ popq(left);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64