DevTools: fix blurry breakpoint tip on retina

third_party/WebKit/Source/devtools/front_end/source_frame/cmdevtools.css

 .CodeMirror {
     line-height: 1.2em !important;
     background-color: transparent !important;
     color: #222;
 }
 
 .CodeMirror-linewidget {
     overflow: visible !important;
 }
 
@@ skipping 75 matching lines @@
 
 .cm-line-without-source-mapping .CodeMirror-linenumber {
     color: rgba(128, 128, 128, 0.4);
 }
 
 .cm-breakpoint.cm-breakpoint-conditional .CodeMirror-linenumber {
     -webkit-border-image: url(Images/breakpointConditional.png) 1 4 1 1;
 }
 
 @media (-webkit-min-device-pixel-ratio: 1.5) {
-.cm-breakpoint .CodeMirror-linenumber {
+.cm-breakpoint .CodeMirror-gutter-wrapper .CodeMirror-linenumber {
     -webkit-border-image: url(Images/breakpoint_2x.png) 2 8 2 2;
 }
 .cm-breakpoint.cm-breakpoint-conditional .CodeMirror-linenumber {
     -webkit-border-image: url(Images/breakpointConditional_2x.png) 2 8 2 2;
 }
 } /* media */
 
 .cm-breakpoint-disabled .CodeMirror-linenumber {
     opacity: 0.5;
 }
@@ skipping 243 matching lines @@
     background-color: transparent;
 }
 
 .-theme-with-dark-background .CodeMirror .CodeMirror-selected {
     background-color: #454545;
 }
 
 .CodeMirror .auto-complete-text{
     color: rgb(128,128,128);
 }