Leverage the fact that we already know the array size in V8Binding's array converting

Source/bindings/v8/V8Binding.h

 /*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 * Copyright (C) 2012 Ericsson AB. 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.
@@ skipping 417 matching lines @@
             *success = true;
 
         v8::Local<v8::Value> v8Value(v8::Local<v8::Value>::New(isolate, value));
         uint32_t length = 0;
         if (value->IsArray())
             length = v8::Local<v8::Array>::Cast(v8Value)->Length();
         else if (toV8Sequence(value, length, isolate).IsEmpty())
             return Vector<RefPtr<T> >();
 
         Vector<RefPtr<T> > result;
+        result.reserveInitialCapacity(length);
         v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(v8Value);
         for (uint32_t i = 0; i < length; ++i) {
             v8::Handle<v8::Value> element = object->Get(i);
 
             if (V8T::HasInstance(element, isolate, worldType(isolate))) {
                 v8::Handle<v8::Object> elementObject = v8::Handle<v8::Object>::Cast(element);
-                result.append(V8T::toNative(elementObject));
+                result.uncheckedAppend(V8T::toNative(elementObject));
             } else {
                 if (success)
                     *success = false;
                 throwTypeError("Invalid Array element type", isolate);
                 return Vector<RefPtr<T> >();
             }
         }
         return result;
     }
 
     // Converts a JavaScript value to an array as per the Web IDL specification:
     // http://www.w3.org/TR/2012/CR-WebIDL-20120419/#es-array
     template <class T>
     Vector<T> toNativeArray(v8::Handle<v8::Value> value, v8::Isolate* isolate)
     {
         v8::Local<v8::Value> v8Value(v8::Local<v8::Value>::New(isolate, value));
         uint32_t length = 0;
         if (value->IsArray())
             length = v8::Local<v8::Array>::Cast(v8Value)->Length();
         else if (toV8Sequence(value, length, isolate).IsEmpty())
             return Vector<T>();
 
         Vector<T> result;
+        result.reserveInitialCapacity(length);
         typedef NativeValueTraits<T> TraitsType;
         v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(v8Value);
         for (uint32_t i = 0; i < length; ++i)
-            result.append(TraitsType::nativeValue(object->Get(i)));
+            result.uncheckedAppend(TraitsType::nativeValue(object->Get(i)));
         return result;
     }
 
     template <class T>
     Vector<T> toNativeArguments(const v8::FunctionCallbackInfo<v8::Value>& args, int startIndex)
     {
         ASSERT(startIndex <= args.Length());
         Vector<T> result;
         typedef NativeValueTraits<T> TraitsType;
         int length = args.Length();
+        result.reserveInitialCapacity(length);
         for (int i = startIndex; i < length; ++i)
-            result.append(TraitsType::nativeValue(args[i]));
+            result.uncheckedAppend(TraitsType::nativeValue(args[i]));
         return result;
     }
 
     Vector<v8::Handle<v8::Value> > toVectorOfArguments(const v8::FunctionCallbackInfo<v8::Value>& args);
 
     // Validates that the passed object is a sequence type per WebIDL spec
     // http://www.w3.org/TR/2012/CR-WebIDL-20120419/#es-sequence
     inline v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value> value, uint32_t& length, v8::Isolate* isolate)
     {
         // Attempt converting to a sequence if the value is not already an array but is
@@ skipping 137 matching lines @@
         return v8::FunctionTemplate::New(function, environment)->GetFunction();
     }
 
     v8::Local<v8::Value> getHiddenValueFromMainWorldWrapper(v8::Isolate*, ScriptWrappable*, v8::Handle<v8::String> key);
 
     v8::Isolate* getIsolateFromScriptExecutionContext(ScriptExecutionContext*);
 
 } // namespace WebCore
 
 #endif // V8Binding_h