Clean up transform methods in GraphicsContext.

Source/core/rendering/svg/RenderSVGResourceFilter.cpp

Index: Source/core/rendering/svg/RenderSVGResourceFilter.cpp
diff --git a/Source/core/rendering/svg/RenderSVGResourceFilter.cpp b/Source/core/rendering/svg/RenderSVGResourceFilter.cpp
index bd2019d089d1db590b3571e6d0ee2b95962bc235..39de4baa53a1e6beecf7f244383ec4d15d1e4b6e 100644
--- a/Source/core/rendering/svg/RenderSVGResourceFilter.cpp
+++ b/Source/core/rendering/svg/RenderSVGResourceFilter.cpp
@@ -150,16 +150,17 @@ static void beginDeferredFilter(GraphicsContext* context, FilterData* filterData
     context->clipRect(boundaries);
     if (filterElement->hasAttribute(SVGNames::filterResAttr)) {
         // Get boundaries in device coords.
+        // FIXME: See crbug.com/382491. Is the use of getCTM OK here, given it does not include device
+        // zoom or High DPI adjustments?
         FloatSize size = context->getCTM().mapSize(boundaries.size());
         // Compute the scale amount required so that the resulting offscreen is exactly filterResX by filterResY pixels.
-        FloatSize filterResScale(
-            filterElement->filterResX()->currentValue()->value() / size.width(),
-            filterElement->filterResY()->currentValue()->value() / size.height());
+        float filterResScaleX = filterElement->filterResX()->currentValue()->value() / size.width();
+        float filterResScaleY = filterElement->filterResY()->currentValue()->value() / size.height();
         // Scale the CTM so the primitive is drawn to filterRes.
-        context->scale(filterResScale);
+        context->scale(filterResScaleX, filterResScaleY);
         // Create a resize filter with the inverse scale.
         AffineTransform resizeMatrix;
-        resizeMatrix.scale(1 / filterResScale.width(), 1 / filterResScale.height());
+        resizeMatrix.scale(1 / filterResScaleX, 1 / filterResScaleY);
         imageFilter = builder.buildTransform(resizeMatrix, imageFilter.get());
     }
     // If the CTM contains rotation or shearing, apply the filter to