DevTools: Normalize whitespace in selector text on editing.

Bug: 767849
Change-Id: Iaa02ed396dd0fde720bebcc276029326b20445a5
Reviewed-on: https://chromium-review.googlesource.com/684098Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504848}

third_party/WebKit/Source/devtools/front_end/elements/StylesSidebarPane.js

@@ -1619,7 +1619,8 @@ Elements.StylePropertiesSection = class {
       return;
 
     element.scrollIntoViewIfNeeded(false);
-    element.textContent = element.textContent;  // Reset selector marks in group.
+    // Reset selector marks in group, and normalize whitespace.
+    element.textContent = element.textContent.replace(/\s+/g, ' ').trim();
 
     var config =
         new UI.InplaceEditor.Config(this.editingSelectorCommitted.bind(this), this.editingSelectorCancelled.bind(this));