DevTools: add entry points for command menu

third_party/WebKit/Source/devtools/front_end/sources/sourcesView.css

Index: third_party/WebKit/Source/devtools/front_end/sources/sourcesView.css
diff --git a/third_party/WebKit/Source/devtools/front_end/sources/sourcesView.css b/third_party/WebKit/Source/devtools/front_end/sources/sourcesView.css
index d32d8ef9e362057c191f69ce79983cebd0bac522..f827d7f426352f81a070fd50dc231f989bfd3aba 100644
--- a/third_party/WebKit/Source/devtools/front_end/sources/sourcesView.css
+++ b/third_party/WebKit/Source/devtools/front_end/sources/sourcesView.css
@@ -92,6 +92,33 @@
     -webkit-user-modify: read-write;
 }
 
+.sources-placeholder {
+    font-size: 14px;
+    text-align: center;
+    margin-top: 20px;
+    text-shadow: rgba(255, 255, 255, 0.75) 0 1px 0;
+    line-height: 2;
+    overflow: hidden;
+}
+
+.sources-placeholder-row {
+    display: flex;
+    text-align: center;
+    white-space: nowrap;
+}
+
+.sources-placeholder-key {
+    flex: 1;
+    text-align: right;
+    padding-right: 15px
+}
+
+.sources-placeholder-value {
+    flex: 1;
+    padding-left: 15px;
+    text-align: left;
+}
+
 @-webkit-keyframes source-frame-value-update-highlight-animation {
     from {
         background-color: inherit;