Implement class id checks as a separate instruction and add a local CSE optimization pass.

runtime/vm/flow_graph_builder.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/flow_graph_builder.h"
 
 #include "vm/ast_printer.h"
 #include "vm/code_descriptors.h"
 #include "vm/dart_entry.h"
 #include "vm/flags.h"
@@ skipping 1951 matching lines @@
   ReturnComputation(store);
 }
 
 
 void EffectGraphVisitor::VisitLoadInstanceFieldNode(
     LoadInstanceFieldNode* node) {
   ValueGraphVisitor for_instance(owner(), temp_index());
   node->instance()->Visit(&for_instance);
   Append(for_instance);
   LoadInstanceFieldComp* load = new LoadInstanceFieldComp(
-      node->field(), for_instance.value(), NULL);
+      node->field(), for_instance.value(), NULL,
+      false);  // Can not deoptimize.
   ReturnComputation(load);
 }
 
 
 void EffectGraphVisitor::VisitStoreInstanceFieldNode(
     StoreInstanceFieldNode* node) {
   ValueGraphVisitor for_instance(owner(), temp_index());
   node->instance()->Visit(&for_instance);
   Append(for_instance);
   ValueGraphVisitor for_value(owner(), for_instance.temp_index());
@@ skipping 431 matching lines @@
   intptr_t len = OS::SNPrint(NULL, 0, kFormat, function_name, reason) + 1;
   char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart