Preparation for combining paths of focus rings and outlines

LayoutTests/platform/linux/svg/custom/scrolling-embedded-svg-file-image-repaint-problem-expected.txt

 {
   "bounds": [1026, 1036],
   "children": [
     {
       "bounds": [1026, 1036],
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
-        [380, 1008, 54, 28],
-        [24, 1012, 737, 20],
-        [24, 1012, 737, 20],
-        [24, 1008, 737, 28],
-        [24, 1008, 737, 28]
+        [384, 1012, 46, 20],
+        [24, 1012, 737, 20]
       ],
       "paintInvalidationClients": [
         "InlineTextBox 'pservers-pattern-01-b \u2190'",
         "InlineTextBox '\n'",
         "InlineTextBox 'index'",
         "InlineTextBox '\n'",
         "InlineTextBox '\u2192 script-handle-01-b'",
         "RootInlineBox",
-        "LayoutBlockFlow DIV class='linkbar'",

[chrishtr, 2015/08/05 03:57:50]

Why are there fewer invalidations here now?

[Xianzhu, 2015/08/05 15:58:43]

This is because we have smaller focus ring overflow, and the div doesn't change
painting size when one of its descendant is focused.

[chrishtr, 2015/08/05 16:53:59]

But what in this CL resulted in the div not changing painting size?

         "LayoutBlockFlow P",
         "LayoutInline A",
         "InlineFlowBox"
       ]
     }
   ]
 }