DevTools: Add test for SourceCodeDiff

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

Index: third_party/WebKit/LayoutTests/inspector/sources/resources/diff-before.css
diff --git a/third_party/WebKit/LayoutTests/inspector/sources/resources/diff-before.css b/third_party/WebKit/LayoutTests/inspector/sources/resources/diff-before.css
new file mode 100644
index 0000000000000000000000000000000000000000..f923f4db395b054938f11d80bffdf9a882a8e6d2
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/inspector/sources/resources/diff-before.css
@@ -0,0 +1,81 @@
+.overflow-auto {
+    overflow: auto;
+}
+
+iframe.widget {
+    position: absolute;
+    width: 100%;
+    height: 100%;
+    left: 0;
+    right: 0;
+    top: 0;
+    bottom: 0;
+}
+
+.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);
+}
+
+button,
+input,
+select {
+    font-family: inherit;
+    font-size: inherit;
+    color: inherit;
+}
+
+input {
+    background-color: white;
+}
+
+.highlighted-search-result.current-search-result {
+    border-radius: 1px;
+    padding: 1px;
+    margin: -1px;
+    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;
+}