Fix getBBox() returning (0,0) bug when width or height is zero

LayoutTests/platform/linux/svg/clip-path/clip-path-pixelation-expected.txt

Index: LayoutTests/platform/linux/svg/clip-path/clip-path-pixelation-expected.txt
diff --git a/LayoutTests/svg/clip-path/clip-path-pixelation-expected.txt b/LayoutTests/platform/linux/svg/clip-path/clip-path-pixelation-expected.txt
similarity index 91%
copy from LayoutTests/svg/clip-path/clip-path-pixelation-expected.txt
copy to LayoutTests/platform/linux/svg/clip-path/clip-path-pixelation-expected.txt
index 66bc6eab566efd8edd8557ae093c5566a047e5bc..c3d692f49d86afb9597283c393510d1023f8eaaa 100644
--- a/LayoutTests/svg/clip-path/clip-path-pixelation-expected.txt
+++ b/LayoutTests/platform/linux/svg/clip-path/clip-path-pixelation-expected.txt
@@ -5,9 +5,9 @@ layer at (0,0) size 800x600
     RenderSVGHiddenContainer {defs} at (0,0) size 0x0
       RenderSVGResourceClipper {clipPath} [id="clip-circle"] [clipPathUnits=objectBoundingBox]
         RenderSVGEllipse {circle} at (0,0) size 1x1 [fill={[type=SOLID] [color=#000000]}] [cx=0.25] [cy=0.25] [r=0.25]
-        RenderSVGEllipse {circle} at (0,0) size 1x1 [fill={[type=SOLID] [color=#000000]}] [cx=0.75] [cy=0.75] [r=0.25]
+        RenderSVGEllipse {circle} at (0,0) size 2x2 [fill={[type=SOLID] [color=#000000]}] [cx=0.75] [cy=0.75] [r=0.25]
     RenderSVGText {text} at (60,5) size 180x19 contains 1 chunk(s)
       RenderSVGInlineText {#text} at (0,0) size 180x19
         chunk 1 (middle anchor) text run 1 at (60.00,20.00) startOffset 0 endOffset 30 width 180.00: "This should not look pixelated"
     RenderSVGRect {rect} at (25,50) size 250x250 [transform={m=((25.00,0.00)(0.00,25.00)) t=(0.00,0.00)}] [fill={[type=SOLID] [color=#008000]}] [x=1.00] [y=2.00] [width=10.00] [height=10.00]
-      [clipPath="clip-circle"] RenderSVGResourceClipper {clipPath} at (1,2) size 10x10
+      [clipPath="clip-circle"] RenderSVGResourceClipper {clipPath} at (-4,-3) size 20x20