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

Source/bindings/v8/V8Binding.h

Index: Source/bindings/v8/V8Binding.h
diff --git a/Source/bindings/v8/V8Binding.h b/Source/bindings/v8/V8Binding.h
index f15a1bc7ba703627b1f53c30a62fe8fa7f2ac359..cbcf7b50a3f05822d395aad7e0f32705e455ff8c 100644
--- a/Source/bindings/v8/V8Binding.h
+++ b/Source/bindings/v8/V8Binding.h
@@ -435,13 +435,14 @@ namespace WebCore {
             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;
@@ -465,10 +466,11 @@ namespace WebCore {
             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;
     }
 
@@ -479,8 +481,9 @@ namespace WebCore {
         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;
     }