Force tiles to swap whenever drawing tree is ready

bug:5632237

Sometimes the drawing tree wouldn't swap it's tiles after a scroll or a view
resize, even though the tiles were painted ready. Now, force all tiles to swap
every time the entire tree is ready.

Change-Id: Id204ed9082b7ee4d41fa712c37febc3dacf6984e
diff --git a/Source/WebCore/platform/graphics/android/TreeManager.cpp b/Source/WebCore/platform/graphics/android/TreeManager.cpp
index 4915f8b..5fbc893 100644
--- a/Source/WebCore/platform/graphics/android/TreeManager.cpp
+++ b/Source/WebCore/platform/graphics/android/TreeManager.cpp
@@ -209,7 +209,7 @@
     if (m_drawingTree) {
         bool drawingReady = didTreeSwap || m_drawingTree->isReady();
 
-        if (didTreeSwap || m_fastSwapMode)
+        if (drawingReady || m_fastSwapMode)
             m_drawingTree->swapTiles();
 
         if (drawingReady) {