Get isolate from thread local instead of (potentially missing) block in HConstant.

R=ulan@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/14284011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14433 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.h

@@ -3249,9 +3249,9 @@ class HConstant: public HTemplateInstruction<0> {
 
   Handle<Object> handle() {
     if (handle_.is_null()) {
-      handle_ = isolate()->factory()->NewNumber(double_value_, TENURED);
+      handle_ = FACTORY->NewNumber(double_value_, TENURED);
     }
-    ALLOW_HANDLE_DEREF(isolate(), "smi check");
+    ALLOW_HANDLE_DEREF(Isolate::Current(), "smi check");
     ASSERT(has_int32_value_ || !handle_->IsSmi());
     return handle_;
   }