Don't force layout of descendants of SVG containers needing self-layout

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

Index: third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp b/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
index 8fd06fc0db188a8df60eb16fcf57986fcdc03415..d89246f7d212aa67df738a083dfaceaf76ce37da 100644
--- a/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
@@ -44,6 +44,7 @@ LayoutSVGRoot::LayoutSVGRoot(SVGElement* node)
     : LayoutReplaced(node)
     , m_objectBoundingBoxValid(false)
     , m_isLayoutSizeChanged(false)
+    , m_didScreenScaleFactorChange(false)
     , m_needsBoundariesOrTransformUpdate(true)
     , m_hasBoxDecorationBackground(false)
     , m_hasNonIsolatedBlendingDescendants(false)
@@ -142,7 +143,12 @@ void LayoutSVGRoot::layout()
     LayoutSize oldSize = size();
     updateLogicalWidth();
     updateLogicalHeight();
+
     buildLocalToBorderBoxTransform();
+    // TODO(fs): Temporarily, needing a layout implies that the local transform
+    // has changed. This should be updated to be more precise and factor in the
+    // actual (relevant) changes to the computed user-space transform.
+    m_didScreenScaleFactorChange = selfNeedsLayout();
 
     SVGLayoutSupport::layoutResourcesIfNeeded(this);
 
@@ -153,10 +159,7 @@ void LayoutSVGRoot::layout()
     // (hence no one is interested in viewport size changes).
     bool layoutSizeChanged = m_isLayoutSizeChanged && svg->hasRelativeLengths();
 
-    bool forceLayoutOfChildren = selfNeedsLayout();
-
-    const bool scalingFactorChanged = false;
-    SVGLayoutSupport::layoutChildren(firstChild(), forceLayoutOfChildren, scalingFactorChanged, layoutSizeChanged);
+    SVGLayoutSupport::layoutChildren(firstChild(), false, m_didScreenScaleFactorChange, layoutSizeChanged);
 
     if (m_needsBoundariesOrTransformUpdate) {
         updateCachedBoundaries();