DevTools: Add features to collect classnames from Stylesheets and DOM

third_party/WebKit/LayoutTests/inspector-protocol/css/resources/collect-class-names.css

+@import "collect-class-names-imported.css" screen;
+
+* {
+    box-sizing: border-box;
+}
+
+html, body, div, a {
+    font-size: 12px;
+}
+
+.test1 {
+    font-size: 12px;
+}
+
+#testdiv > .test2 {

[dgozman, 2016/09/09 01:57:56]

Let's have duplicates in this file to check they are not duplicated in protocol
response.

[ahmetemirercin, 2016/09/09 10:07:55]

Done.

+    font-size: 12px;
+}
+
+.test3 > .test4 {
+    font-size: 12px;
+}
+
+.test5.test6 {
+    font-size: 12px;
+}
+
+.test7 div .test8 > a {
+    font-size: 12px;
+}
+
+.test9:first-child.test10 > .test11 {
+    font-size: 12px;
+}
+
+.test12.test13:last-child {
+    font-size: 12px;
+}
+
+@media (min-width: 1px) {
+    .test14 {
+        font-size: 12px;
+    }
+    #testid > .test15 {
+        font-size: 12px;
+    }
+}
+
+@supports (display: flex) {
+    .support-class {
+      display: -webkit-flex;
+    }
+}