am af2af4e5: Add proper support for fixed position elements

    private void drawLayers(Canvas canvas) {

        if (mRootLayer != 0) {

            float scrollY = Math.max(mScrollY - getTitleHeight(), 0);

            int scrollY = computeVerticalScrollOffset();

            int viewHeight = getHeight() - getVisibleTitleHeight();

            nativeDrawLayers(mRootLayer, mScrollX, scrollY,

                             getWidth(), viewHeight,

                             mActualScale, canvas);

        }

    }

    private native boolean  nativeLayersHaveAnimations(int layer);

    private native void     nativeUpdateLayers(int layer, int updates);

    private native void     nativeDrawLayers(int layer,

                                             float scrollX, float scrollY,

                                             int scrollX, int scrollY,

                                             int width, int height,

                                             float scale, Canvas canvas);

    private native void     nativeDrawMatches(Canvas canvas);

    private native void     nativeDrawSelectionPointer(Canvas content,