Force full invalidation after layoutScope.setNeedsLayout() in...

Force full invalidation after layoutScope.setNeedsLayout() in PaintLayerScrollableArea::finalizeScrollDimensions()

This is a partial revert of https://codereview.chromium.org/799093002
which caused the bug.

This is a temporary measure to workaround crbug.com/560418
for crbug.com/535161.

BUG=535161,560418

Review URL: https://codereview.chromium.org/1471453002

Cr-Commit-Position: refs/heads/master@{#361215}

third_party/WebKit/LayoutTests/fast/repaint/destroy-scrollbar-expected.txt

@@ -6,10 +6,12 @@
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
-        [185, 100, 15, 200]
+        [185, 100, 15, 200],
+        [0, 100, 200, 200]
       ],
       "paintInvalidationClients": [
         "VerticalScrollbar",
+        "LayoutBlockFlow (positioned) DIV",
         "LayoutBlockFlow (positioned) DIV"
       ]
     }

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp

@@ -676,6 +676,9 @@ void PaintLayerScrollableArea::finalizeScrollDimensions(const DoubleSize& origin
                 m_inOverflowRelayout = true;
                 SubtreeLayoutScope layoutScope(box());
                 layoutScope.setNeedsLayout(&box(), LayoutInvalidationReason::ScrollbarChanged);
+                // TODO(wangxianzhu): Remove the following statement when paint invalidation
+                // can detect client box changes. crbug.com/560418.
+                box().setShouldDoFullPaintInvalidation();
                 if (box().isLayoutBlock()) {
                     LayoutBlock& block = toLayoutBlock(box());
                     block.scrollbarsChanged(autoHorizontalScrollBarChanged, autoVerticalScrollBarChanged);