Optimize typed-array length loading.

src/hydrogen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1964 matching lines @@
     bool IsStringLength() {
       return map_->instance_type() < FIRST_NONSTRING_TYPE &&
           name_->Equals(isolate()->heap()->length_string());
     }
 
     bool IsArrayLength() {
       return map_->instance_type() == JS_ARRAY_TYPE &&
           name_->Equals(isolate()->heap()->length_string());
     }
 
+    bool IsTypedArrayLength() {
+      return map_->instance_type() == JS_TYPED_ARRAY_TYPE &&
+          name_->Equals(isolate()->heap()->length_string());
+    }
+
     bool has_holder() { return !holder_.is_null(); }
 
     LookupResult* lookup() { return &lookup_; }
     Handle<Map> map() { return map_; }
     Handle<JSObject> holder() { return holder_; }
     Handle<JSFunction> accessor() { return accessor_; }
     Handle<Object> constant() { return constant_; }
     HObjectAccess access() { return access_; }
 
    private:
@@ skipping 370 matching lines @@
   }
 
  private:
   HGraphBuilder* builder_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_