DevTools: Add test for SourceCodeDiff

third_party/WebKit/LayoutTests/inspector/sources/resources/diff-after.css

+iframe.widget {
+    position: absolute;
+    width: 100%;

[lushnikov, 2016/09/29 21:10:33]

i failed to diff this against the other version manually. Imaging test start
failing - it would be hard to understand what's going on

Let's come up with something small and human-verifiable

[einbinder, 2016/09/29 22:33:17]

Done.

+    height: 100%;
+    left: 10px;
+    right: 10px;
+    top: 10px;
+    bottom: 10px;
+}
+
+.hidden {
+    display: none !important;
+}
+
+.monospace {
+    font-size: 10px !important;
+    font-family: monospace;
+}
+
+.highlighted-search-result {
+    border-radius: 1px;
+    padding: 1px;
+    margin: -1px;
+    background-color: rgba(255, 255, 0, 0.8);
+}
+
+.-theme-with-dark-background .highlighted-search-result,
+:host-context(.-theme-with-dark-background) .highlighted-search-result {
+    background-color: hsl(133, 100%, 30%);
+    color: #333;
+}
+
+.link {
+    cursor: pointer;
+    text-decoration: underline;
+    color: rgb(17, 85, 204);
+}
+
+input {
+    background-color: white;
+}
+
+:host-context(.-theme-with-dark-background) input[type="checkbox"]::not(.-theme-preserve) {
+    -webkit-filter: invert(80%);
+}
+
+input[type="search"]:focus,
+input[type="text"]:focus {
+    outline: auto rgb(56, 121, 217);
+}
+
+.highlighted-search-result.current-search-result {
+    border-radius: 1px;
+    padding: 100px;
+    background-color: rgba(255, 127, 0, 0.8);
+}
+
+.dimmed {
+    opacity: 0.6;
+}
+
+.editing {
+    -webkit-user-select: text;
+    box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.2),
+                0 2px 4px rgba(0, 0, 0, 0.2),
+                0 2px 6px rgba(0, 0, 0, 0.1);
+    background-color: white;
+    -webkit-user-modify: read-write-plaintext-only;
+    text-overflow: clip !important;
+    padding-left: 2px;
+    margin-left: -2px;
+    padding-right: 2px;
+    margin-right: -2px;
+    margin-bottom: -1px;
+    padding-bottom: 1px;
+    opacity: 1.0 !important;
+}