Hoist "layout size changed" check out of SVGLayoutSupport::layoutChildren

third_party/WebKit/Source/core/layout/svg/LayoutSVGHiddenContainer.cpp

 /*
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 17 matching lines @@
     : LayoutSVGContainer(element)
 {
 }
 
 void LayoutSVGHiddenContainer::layout()
 {
     ASSERT(needsLayout());
     LayoutAnalyzer::Scope analyzer(*this);
     // TODO(fs): In what cases do we need this?
     bool transformChanged = SVGLayoutSupport::transformToRootChanged(this);
-    SVGLayoutSupport::layoutChildren(this, selfNeedsLayout(), transformChanged);
+
+    // When hasRelativeLengths() is false, no descendants have relative lengths
+    // (hence no one is interested in viewport size changes).
+    bool layoutSizeChanged = element()->hasRelativeLengths()
+        && SVGLayoutSupport::layoutSizeOfNearestViewportChanged(this);
+
+    SVGLayoutSupport::layoutChildren(this, selfNeedsLayout(), transformChanged, layoutSizeChanged);
     updateCachedBoundaries();
     clearNeedsLayout();
 }
 
 void LayoutSVGHiddenContainer::paint(const PaintInfo&, const LayoutPoint&) const
 {
     // This subtree does not paint.
 }
 
 void LayoutSVGHiddenContainer::absoluteQuads(Vector<FloatQuad>&) const
 {
     // This subtree does not take up space or paint
 }
 
 bool LayoutSVGHiddenContainer::nodeAtFloatPoint(HitTestResult&, const FloatPoint&, HitTestAction)
 {
     return false;
 }
 
 } // namespace blink