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

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 0c3ee1dc081101e47646daa14e0c1beb464f9ceb..b4d26694a253a8c1c4de95a3228d445f4ab7cf84 100644
--- a/src/hydrogen-instructions.h
+++ b/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_;
   }