Optimize Crankshaft array literal initialization from boilerplate.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 953d417f8c97a50f983b18be7b72ef5090e3fb26..dce81a1e381fa3816505caea930f3978dde46a0b 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -4156,18 +4156,21 @@ class HMaterializedLiteral: public HTemplateInstruction<V> {
 class HArrayLiteral: public HMaterializedLiteral<1> {
  public:
   HArrayLiteral(HValue* context,
-                Handle<FixedArray> constant_elements,
+                Handle<JSObject> boilerplate_object,
                 int length,
                 int literal_index,
                 int depth)
       : HMaterializedLiteral<1>(literal_index, depth),
         length_(length),
-        constant_elements_(constant_elements) {
+        boilerplate_object_(boilerplate_object) {
     SetOperandAt(0, context);
   }
 
   HValue* context() { return OperandAt(0); }
-  Handle<FixedArray> constant_elements() const { return constant_elements_; }
+  ElementsKind boilerplate_elements_kind() const {
+    return boilerplate_object_->GetElementsKind();
+  }
+  Handle<JSObject> boilerplate_object() const { return boilerplate_object_; }
   int length() const { return length_; }
 
   bool IsCopyOnWrite() const;
@@ -4181,7 +4184,7 @@ class HArrayLiteral: public HMaterializedLiteral<1> {
 
  private:
   int length_;
-  Handle<FixedArray> constant_elements_;
+  Handle<JSObject> boilerplate_object_;
 };