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

LayoutTests/platform/linux/svg/custom/getscreenctm-in-scrollable-svg-area-expected.txt

Index: LayoutTests/platform/linux/svg/custom/getscreenctm-in-scrollable-svg-area-expected.txt
diff --git a/LayoutTests/platform/win/svg/custom/getscreenctm-in-scrollable-svg-area-expected.txt b/LayoutTests/platform/linux/svg/custom/getscreenctm-in-scrollable-svg-area-expected.txt
similarity index 87%
copy from LayoutTests/platform/win/svg/custom/getscreenctm-in-scrollable-svg-area-expected.txt
copy to LayoutTests/platform/linux/svg/custom/getscreenctm-in-scrollable-svg-area-expected.txt
index ec84f8e72c927be527562d654f74c400b2c798fb..2dff42e14e7d742c9d115a151fd5c43db2582e5d 100644
--- a/LayoutTests/platform/win/svg/custom/getscreenctm-in-scrollable-svg-area-expected.txt
+++ b/LayoutTests/platform/linux/svg/custom/getscreenctm-in-scrollable-svg-area-expected.txt
@@ -3,9 +3,9 @@ layer at (0,0) size 785x4005
 layer at (0,0) size 785x4005
   RenderBlock {html} at (0,0) size 785x4005
     RenderBody {body} at (0,0) size 785x4005
-      RenderSVGRoot {svg} at (276,1950) size 248x154
+      RenderSVGRoot {svg} at (276,1949) size 248x155
         RenderSVGRect {rect} at (350,1950) size 100x100 [fill={[type=SOLID] [color=#000080] [opacity=0.50]}] [x=350.00] [y=1950.00] [width=100.00] [height=100.00]
-        RenderSVGEllipse {circle} at (350,1950) size 100x100 [fill={[type=SOLID] [color=#F08080]}] [cx=400.00] [cy=2000.00] [r=50.00]
+        RenderSVGEllipse {circle} at (349,1949) size 102x102 [fill={[type=SOLID] [color=#F08080]}] [cx=400.00] [cy=2000.00] [r=50.00]
         RenderSVGText {text} at (276,2085) size 248x19 contains 1 chunk(s)
           RenderSVGInlineText {#text} at (0,0) size 247x19
             chunk 1 (middle anchor) text run 1 at (276.50,2100.00) startOffset 0 endOffset 46 width 247.00: "The test passes if the circle sits in the rect"