DevTools: Use CodeMirror modes instead of highlight tokenizers

Source/devtools/front_end/cm/cmdevtools.css

 .CodeMirror * {
   box-sizing: content-box;
 }
 
 .CodeMirror {
   line-height: 1.2em !important;
   background-color: transparent !important;
 }
 
 .CodeMirror .source-frame-eval-expression {
@@ skipping 177 matching lines @@
     border-top-right-radius: 1px;
     border-bottom-right-radius: 1px;
 }
 
 .cm-line-with-selection .cm-column-with-selection.cm-search-highlight:before {
     margin: -1px -1px -1px -1px;
     background-color: rgb(241, 234, 0);
     z-index: -1;
 }
 
-span.cm-js-keyword {color: rgb(170, 13, 145);}
-span.cm-js-number {color: rgb(28, 0, 207);}
-span.cm-js-comment {color: rgb(0, 116, 0);}
-span.cm-js-string {color: rgb(196, 26, 22);}
-span.cm-js-string-2 {color: rgb(196, 26, 22);}
-
-span.cm-css-keyword { color: rgb(7, 144, 154);}
-span.cm-css-number {color: rgb(50, 0, 255);}
-span.cm-css-comment {color: rgb(0, 116, 0);}
-span.cm-css-def {color: rgb(200, 0, 0);}
-span.cm-css-meta {color: rgb(200, 0, 0);}
-span.cm-css-atom {color: rgb(7, 144, 154);}
-span.cm-css-string {color: rgb(7, 144, 154);}
-span.cm-css-string-2 {color: rgb(7, 144, 154);}
-span.cm-css-link {color: rgb(7, 144, 154);}
-span.cm-css-variable {color: rgb(200, 0, 0);}
-span.cm-css-variable-2 {color: rgb(0, 0, 128);}
-span.cm-css-property {color: rgb(200, 0, 0);}
-
-span.cm-xml-meta {color: rgb(192, 192, 192);}
-span.cm-xml-comment {color: rgb(35, 110, 37);}
-span.cm-xml-string {color: rgb(26, 26, 166);}
-span.cm-xml-tag {color: rgb(136, 18, 128);}
-span.cm-xml-attribute {color: rgb(153, 69, 0);}
-span.cm-xml-link {color: #00e;}
-
 .CodeMirror .webkit-html-message-bubble {
     box-shadow: black 0px 2px 5px;
     border-radius: 9px;
     -webkit-border-fit: lines;
     font-size: 10px;
     font-family: Lucida Grande, sans-serif;
     font-weight: bold;
     margin: 3px 10px;
     padding: 1px 2px 0;
     z-index: 5;
 }
 
 .CodeMirror .webkit-html-message-bubble img {
     position: relative;
     top: 1px;
     margin-right: 2px;
 }
 
 .CodeMirror .webkit-html-warning-message {
     background-color: rgb(100%, 62%, 42%);
     border: 2px solid rgb(100%, 52%, 21%);
 }
 
 .CodeMirror .webkit-html-error-message {
     background-color: rgb(100%, 42%, 42%);
     border: 2px solid rgb(100%, 31%, 31%);
 }