Make sure <url>s are being serialized according to spec

third_party/WebKit/LayoutTests/inspector/elements/styles-2/inject-stylesheet-expected.txt

 CONSOLE MESSAGE: line 10: iframe loaded
 Tests that injected user stylesheets are reflected in the Styles pane.
 
 
 Main frame style:
 background-attachment: scroll
     initial - #main inject-stylesheet.html:5 -> inject-stylesheet.html:5:3
 background-clip: border-box
     initial - #main inject-stylesheet.html:5 -> inject-stylesheet.html:5:3
 background-color: rgb(0, 0, 255)
     blue - #main inject-stylesheet.html:5 -> inject-stylesheet.html:5:3
 background-image: none
     initial - #main inject-stylesheet.html:5 -> inject-stylesheet.html:5:3
 background-origin: padding-box
     initial - #main inject-stylesheet.html:5 -> inject-stylesheet.html:5:3
 background-size: auto
     initial - #main inject-stylesheet.html:5 -> inject-stylesheet.html:5:3
 color: rgb(255, 0, 0)
     red - #main injected stylesheet
 display: block
     block - div user agent stylesheet
--webkit-border-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAQAAAC1+jfqAAAAiElEQ…Ms+LS30CAhBN5nNxeT5hbJ1zwmji2k+aF6NENIPf/hs54f0sZFUVAMigAAAABJRU5ErkJggg==) 100% / 1 / 0px stretch
-    url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAQAAAC1+jfqAAAAiElEQ…Ms+LS30CAhBN5nNxeT5hbJ1zwmji2k+aF6NENIPf/hs54f0sZFUVAMigAAAABJRU5ErkJggg==) - #main injected stylesheet
+-webkit-border-image: url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAQAAAC1+jfqAAAAiElE…s+LS30CAhBN5nNxeT5hbJ1zwmji2k+aF6NENIPf/hs54f0sZFUVAMigAAAABJRU5ErkJggg==") 100% / 1 / 0px stretch
+    url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAQAAAC1+jfqAAAAiElE…s+LS30CAhBN5nNxeT5hbJ1zwmji2k+aF6NENIPf/hs54f0sZFUVAMigAAAABJRU5ErkJggg==") - #main injected stylesheet
 [expanded] 
 element.style  { ()
 
 [expanded] 
 media="screen" (inject-stylesheet.html)
 #main  { (inject-stylesheet.html:5 -> inject-stylesheet.html:5:3)
     background: blue;
         background-image: initial;
         background-position-x: initial;
         background-position-y: initial;
         background-size: initial;
         background-repeat-x: initial;
         background-repeat-y: initial;
         background-attachment: initial;
         background-origin: initial;
         background-clip: initial;
         background-color: blue;
 
 [expanded] 
 #main  { (injected stylesheet)
     color: red;
-    -webkit-border-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAQAAAC1+jfqAAAAiElEQ…Ms+LS30CAhBN5nNxeT5hbJ1zwmji2k+aF6NENIPf/hs54f0sZFUVAMigAAAABJRU5ErkJggg==);
+    -webkit-border-image: url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAQAAAC1+jfqAAAAiElE…s+LS30CAhBN5nNxeT5hbJ1zwmji2k+aF6NENIPf/hs54f0sZFUVAMigAAAABJRU5ErkJggg==");
 
 [expanded] 
 div  { (user agent stylesheet)
     display: block;
 
 iframe style:
 background-attachment: scroll
     initial - #iframebody injected stylesheet
     OVERLOADED initial - body inject-styleshe…me-data.html:4 -> inject-stylesheet-iframe-data.html:4:3
 background-clip: border-box
@@ skipping 56 matching lines @@
 [expanded] 
 body  { (user agent stylesheet)
     display: block;
     margin: 8px;
         margin-top: 8px;
         margin-right: 8px;
         margin-bottom: 8px;
         margin-left: 8px;