DevTools: shard inspector/elements tests for faster execution.

LayoutTests/inspector/elements/styles-1/css-outline-expected.txt

 The test verifies the CSS outline functionality.
 
 {
     atRule : "@import url("some-url-to-load-css.css") print"
     columnNumber : 0
     lineNumber : 1
 }
 {
     atRule : "@charset "ISO-8859-15""
     columnNumber : 0
@@ skipping 106 matching lines @@
             value : "10px"
         }
         {
             name : "font-family"
             value : ""Example Font""
         }
     ]
     selectorText : "span"
 }