Use GeometryMapper in PaintInvalidator

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

Index: third_party/WebKit/Source/core/paint/SVGRootPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/SVGRootPainter.cpp b/third_party/WebKit/Source/core/paint/SVGRootPainter.cpp
index 14781968a9586066b8e4fc87adf5483ef4b190d7..b4a2d1f996b8e64e4f8440f54ae7e05dea6c6950 100644
--- a/third_party/WebKit/Source/core/paint/SVGRootPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/SVGRootPainter.cpp
@@ -28,9 +28,12 @@ AffineTransform SVGRootPainter::transformToPixelSnappedBorderBox(const LayoutPoi
     const IntRect snappedSize = pixelSnappedSize(paintOffset);
     AffineTransform paintOffsetToBorderBox =
         AffineTransform::translation(snappedSize.x(), snappedSize.y());
-    paintOffsetToBorderBox.scale(
-        snappedSize.width() / m_layoutSVGRoot.size().width().toFloat(),
-        snappedSize.height() / m_layoutSVGRoot.size().height().toFloat());
+    LayoutSize size = m_layoutSVGRoot.size();
+    if (!size.isEmpty()) {

[pdr., 2016/08/12 17:59:58]

If the size is empty, should we be painting anything? Could we change the
early-out at the beginning from:
if (pixelSnappedSize(paintOffset).isEmpty())
to:
if (m_layoutSVGRoot.size())

?

[Xianzhu, 2016/08/12 18:22:39]

I wonder if the early return in SVGRootPaint::paint() is correct. What if the
svg root doesn't clip children even if its size is empty?

The added check is for the callsite in
PaintPropertyTreeBuilder::updateSvgLocalToBorderBoxTransform() which doesn't
have the early return like paint().

+        paintOffsetToBorderBox.scale(
+            snappedSize.width() / size.width().toFloat(),
+            snappedSize.height() / size.height().toFloat());
+    }
     paintOffsetToBorderBox.multiply(m_layoutSVGRoot.localToBorderBoxTransform());
     return paintOffsetToBorderBox;
 }