Merge 184652 "Disallow non-flexbox child renderers for RenderMedia"

Source/core/rendering/RenderMedia.cpp

Index: Source/core/rendering/RenderMedia.cpp
===================================================================
--- Source/core/rendering/RenderMedia.cpp	(revision 185109)
+++ Source/core/rendering/RenderMedia.cpp	(working copy)
@@ -77,6 +77,16 @@
     clearNeedsLayout();
 }
 
+bool RenderMedia::isChildAllowed(RenderObject* child, RenderStyle*) const
+{
+    // The only allowed child is the media controls. The user agent stylesheet
+    // (mediaControls.css) has ::-webkit-media-controls { display: flex; }. If
+    // author style sets display: inline we would get an inline renderer as a
+    // child of replaced content, which is not supposed to be possible. This
+    // check can be removed if ::-webkit-media-controls is made internal.
+    return child->isFlexibleBox();
+}
+
 void RenderMedia::paintReplaced(PaintInfo&, const LayoutPoint&)
 {
 }