unlink codemirror doc on component unmount (firefox-devtools#2129)

Author: juliandescottes

src/components/Editor/index.js

@@ -201,7 +201,10 @@ const Editor = React.createClass({
     resizeBreakpointGutter(codeMirror);
     debugGlobal("cm", codeMirror);
 
-    if (this.props.sourceText) {
+    if (this.props.selectedSource) {
+      let sourceId = this.props.selectedSource.get("id");
+      this.editor.replaceDocument(getDocument(sourceId));
+    } else if (this.props.sourceText) {
       this.setText(this.props.sourceText.get("text"));
     }
   },

src/utils/editor/source-editor.js

@@ -49,7 +49,10 @@ class SourceEditor {
   }
 
   destroy() {
-    // No need to do anything.
+    // Unlink the current document.
+    if (this.editor.doc) {
+      this.editor.doc.cm = null;
+    }
   }
 
   get codeMirror(): any {