Align reference box computation for inline boxes with Gecko

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2043 matching lines @@
         }
     }
 
     return resultLayer;
 }
 
 LayoutRect PaintLayer::boxForClipPath() const
 {
     if (!layoutObject()->isBox()) {
         SECURITY_DCHECK(layoutObject()->isLayoutInline());
-        return toLayoutInline(layoutObject())->linesBoundingBox();
+        const LayoutInline& layoutInline = toLayoutInline(*layoutObject());
+        // This somewhat convoluted computation matches what Gecko does.
+        // See crbug.com/641907.
+        LayoutRect inlineBBox = layoutInline.linesBoundingBox();
+        const InlineFlowBox* flowBox = layoutInline.firstLineBox();
+        inlineBBox.setHeight(flowBox ? flowBox->frameRect().height() : LayoutUnit(0));
+        return inlineBBox;
     }
     return toLayoutBox(layoutObject())->borderBoxRect();
 }
 
 bool PaintLayer::hitTestClippedOutByClipPath(PaintLayer* rootLayer, const HitTestLocation& hitTestLocation) const
 {
     if (!layoutObject()->hasClipPath())
         return false;
     DCHECK(isSelfPaintingLayer());
     DCHECK(rootLayer);
@@ skipping 873 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif