Bug 758531: Prevent leaking Azure Patterns' GradientStops. r=roc

gfx/thebes/gfxPattern.cpp

@@ -1,4 +1,4 @@
-/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
@@ -122,6 +122,11 @@ gfxPattern::GetMatrix() const
 Pattern*
 gfxPattern::GetPattern(DrawTarget *aTarget, Matrix *aPatternTransform)
 {
+  if (mGfxPattern) {
+    mGfxPattern->~Pattern();
+    mGfxPattern = nsnull;
+  }
+
   if (!mPattern) {
     mGfxPattern = new (mSurfacePattern.addr())
       SurfacePattern(mSourceSurface, EXTEND_CLAMP, mTransform);