Bug 1346662 - do not revert original text after saving; r=gl

When saving an original style sheet, arrange not to reload the text
from the OriginalSourceActor afterward.  The actor will serve stale
text, but the editor knows better already.

MozReview-Commit-ID: BcMaSSB1uhA

--HG--
extra : rebase_source : 5023f67d17d1702dcd4b1c8fb13562e08d115b18

devtools/client/styleeditor/StyleSheetEditor.jsm

@@ -358,6 +358,7 @@ StyleSheetEditor.prototype = {
       // We just applied an edit in the editor, so we can drop this
       // notification.
       this._isUpdating = false;
+      this.emit("style-applied");
     } else if (this.sourceEditor) {
       this._getSourceTextAndPrettify().then((newText) => {
         this._justSetText = true;
@@ -742,6 +743,9 @@ StyleSheetEditor.prototype = {
       let decoder = new TextDecoder();
       let text = decoder.decode(array);
 
+      // Ensure we don't re-fetch the text from the original source
+      // actor when we're notified that the style sheet changed.
+      this._isUpdating = true;
       let relatedSheet = this.styleSheet.relatedStyleSheet;
       relatedSheet.update(text, this.transitionsEnabled);
     }, this.markLinkedFileBroken);

devtools/client/styleeditor/test/browser_styleeditor_sourcemap_watching.js

@@ -73,6 +73,9 @@ add_task(function* () {
 
   color = yield getComputedStyleProperty({selector: "div", name: "color"});
   is(color, "rgb(0, 0, 255)", "div is blue after saving file");
+
+  // Ensure that the editor didn't revert.  Bug 1346662.
+  is(editor.sourceEditor.getText(), CSS_TEXT, "edits remain applied");
 });
 
 function editSCSS(editor) {