DevTools: [SSP] consume event if it inserts a new property

Source/devtools/front_end/elements/StylesSidebarPane.js

Index: Source/devtools/front_end/elements/StylesSidebarPane.js
diff --git a/Source/devtools/front_end/elements/StylesSidebarPane.js b/Source/devtools/front_end/elements/StylesSidebarPane.js
index c859f563eab841350621302908d0932ab2a20ac1..05a034b0a2a41dc064d46956a285779a25031a0f 100644
--- a/Source/devtools/front_end/elements/StylesSidebarPane.js
+++ b/Source/devtools/front_end/elements/StylesSidebarPane.js
@@ -1599,8 +1599,10 @@ WebInspector.StylePropertiesSection.prototype = {
     {
         if (this._checkWillCancelEditing() || !this.editable)
             return;
-        if (event.target === this._selectorContainer)
+        if (event.target === this._selectorContainer) {
             this.addNewBlankProperty(0).startEditing();
+            event.consume(true);
+        }
     },
 
     /**
@@ -1697,6 +1699,7 @@ WebInspector.StylePropertiesSection.prototype = {
         }
         this.expand();
         this.addNewBlankProperty().startEditing();
+        event.consume(true)
     },
 
     _handleSelectorClick: function(event)