Enables unboxed mints in ia32 javascript int compatability mode.

runtime/vm/intermediate_language.h

 // 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.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
 #include "vm/handles_impl.h"
 #include "vm/locations.h"
 #include "vm/object.h"
 
 namespace dart {
 
+DECLARE_FLAG(bool, throw_on_javascript_int_overflow);
+
 class BitVector;
 class BlockEntryInstr;
 class BufferFormatter;
 class CatchBlockEntryInstr;
 class ComparisonInstr;
 class ControlInstruction;
 class Definition;
 class Environment;
 class FlowGraph;
 class FlowGraphBuilder;
@@ skipping 5773 matching lines @@
   }
 
   Value* left() const { return inputs_[0]; }
   Value* right() const { return inputs_[1]; }
 
   Token::Kind op_kind() const { return op_kind_; }
 
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
   virtual bool CanDeoptimize() const {
-    return (op_kind() == Token::kADD) || (op_kind() == Token::kSUB);
+    return FLAG_throw_on_javascript_int_overflow ||
+        (op_kind() == Token::kADD) || (op_kind() == Token::kSUB);
   }
 
   virtual Representation representation() const {
     return kUnboxedMint;
   }
 
   virtual Representation RequiredInputRepresentation(intptr_t idx) const {
     ASSERT((idx == 0) || (idx == 1));
     return kUnboxedMint;
   }
@@ skipping 93 matching lines @@
     // Override generated deopt-id.
     deopt_id_ = deopt_id;
   }
 
   Value* value() const { return inputs_[0]; }
 
   Token::Kind op_kind() const { return op_kind_; }
 
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
-  virtual bool CanDeoptimize() const { return false; }
+  virtual bool CanDeoptimize() const {
+    return FLAG_throw_on_javascript_int_overflow;
+  }
 
   virtual Representation representation() const {
     return kUnboxedMint;
   }
 
   virtual Representation RequiredInputRepresentation(intptr_t idx) const {
     ASSERT(idx == 0);
     return kUnboxedMint;
   }
 
@@ skipping 691 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_