Add a hack to set shouldPaint to true for force-composited iframes.

third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
index 9f1040f77cd9b2663f2feb5bae526776a416999f..eb5e85d6c7bc940f1da280dfae0531828645dbc5 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -3281,7 +3281,7 @@ void LayoutBlockFlow::addOverhangingFloats(LayoutBlockFlow* child, bool makeChil
                 bool shouldPaint = false;
 
                 // The nearest enclosing layer always paints the float (so that zindex and stacking
-                // behaves properly). We always want to propagate the desire to paint the float as
+            // behaves properly). We always want to propagate the desire to paint the float as

[Xianzhu, 2016/05/26 18:29:54]

Nit: Unnecessary change

[chrishtr, 2016/05/26 18:49:29]

Done.

                 // far out as we can, to the outermost block that overlaps the float, stopping only
                 // if we hit a self-painting layer boundary.
                 if (floatingObject.layoutObject()->enclosingFloatPaintingLayer() == enclosingFloatPaintingLayer() && !floatingObject.isLowestNonOverhangingFloatInChild()) {
@@ -3378,7 +3378,7 @@ bool LayoutBlockFlow::hitTestFloats(HitTestResult& result, const HitTestLocation
     for (FloatingObjectSetIterator it = floatingObjectSet.end(); it != begin;) {
         --it;
         const FloatingObject& floatingObject = *it->get();
-        if (floatingObject.shouldPaint() && !floatingObject.layoutObject()->hasSelfPaintingLayer()) {
+        if (floatingObject.shouldPaint()) {
             LayoutUnit xOffset = xPositionForFloatIncludingMargin(floatingObject) - floatingObject.layoutObject()->location().x();
             LayoutUnit yOffset = yPositionForFloatIncludingMargin(floatingObject) - floatingObject.layoutObject()->location().y();
             LayoutPoint childPoint = flipFloatForWritingModeForChild(floatingObject, adjustedLocation + LayoutSize(xOffset, yOffset));