Counteract idiot frameworks that set box-sizing to border-box

Issue #1060

lib/codemirror.css

@@ -118,6 +118,8 @@ div.CodeMirror span.CodeMirror-nonmatchingbracket {color: #f22;}
   height: 100%;
   outline: none; /* Prevent dragging from highlighting the element */
   position: relative;
+  -moz-box-sizing: content-box;
+  box-sizing: content-box;
 }
 .CodeMirror-sizer {
   position: relative;
@@ -156,6 +158,8 @@ div.CodeMirror span.CodeMirror-nonmatchingbracket {color: #f22;}
 .CodeMirror-gutter {
   white-space: normal;
   height: 100%;
+  -moz-box-sizing: content-box;
+  box-sizing: content-box;
   padding-bottom: 30px;
   margin-bottom: -32px;
   display: inline-block;