DevTools: remove unused CSS.

See:
https://codereview.chromium.org/526423002

BUG=
NOTRY=true

Review URL: https://codereview.chromium.org/553753002

git-svn-id: svn://svn.chromium.org/blink/trunk@181545 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/devtools/front_end/responsiveDesignView.css

@@ -439,14 +439,6 @@
     flex: none;
 }
 
-.responsive-design-ruler-glasspane {
-    position: absolute;
-    left: 0;
-    right: 0;
-    top: 0;
-    background-color: transparent;
-}
-
 .responsive-design-toggle-media-inspector .glyph {
     background-color: rgb(180, 180, 180);
     -webkit-mask-position: -128px -48px;
@@ -563,29 +555,3 @@
 .media-inspector-label-left {
     left: 2px;
 }
-
-/* Media query serifs on ruler */
-
-.media-inspector-threshold {
-    position: absolute;
-    top: 0px;
-    bottom: 0px;
-    width: 5px;
-    margin-left: -2px;
-}
-
-.media-inspector-threshold::before {
-    content: ".";
-    color: transparent;
-    position: absolute;
-    left: 2px;
-    right: 2px;
-    top: 0px;
-    bottom: 0px;
-    box-sizing: border-box;
-    border-left: 1px solid rgb(204, 104, 31);
-}
-
-.media-inspector-threshold:hover {
-    background-color: rgb(204, 104, 31);
-}