Bug 1146935 - StyleEditor: Respect the transition preference when a linked CSS file has changed on disk. r=bgrins

This should fix intermittent browser_styleeditor_sourcemap_watching.js
which was disabling transitions to avoid races between the transition
finishing and the 'style-applied' event to be sent from the server.

--HG--
extra : transplant_source : %1B%AB1%F3%23%28%85%0DZLe%9B%9E-%EEH%F54m%99

devtools/client/styleeditor/StyleSheetEditor.jsm

@@ -190,6 +190,15 @@ StyleSheetEditor.prototype = {
     return this._friendlyName;
   },
 
+  /**
+   * Check if transitions are enabled for style changes.
+   *
+   * @return Boolean
+   */
+  get transitionsEnabled() {
+    return Services.prefs.getBoolPref(TRANSITION_PREF);
+  },
+
   /**
    * If this is an original source, get the path of the CSS file it generated.
    */
@@ -495,9 +504,7 @@ StyleSheetEditor.prototype = {
       this._state.text = this.sourceEditor.getText();
     }
 
-    let transitionsEnabled = Services.prefs.getBoolPref(TRANSITION_PREF);
-
-    this.styleSheet.update(this._state.text, transitionsEnabled)
+    this.styleSheet.update(this._state.text, this.transitionsEnabled)
                    .then(null, Cu.reportError);
   },
 
@@ -683,7 +690,7 @@ StyleSheetEditor.prototype = {
       let text = decoder.decode(array);
 
       let relatedSheet = this.styleSheet.relatedStyleSheet;
-      relatedSheet.update(text, true);
+      relatedSheet.update(text, this.transitionsEnabled);
     }, this.markLinkedFileBroken);
   },