Enable the object-shorthand ESLint rule in web

Please see http://eslint.org/docs/rules/object-shorthand.

For the most part, these changes are of the search-and-replace kind, and the previously enabled `no-undef` rule should complement the tests in helping ensure that no stupid errors crept into to the patch.

web/overlay_manager.js

@@ -39,10 +39,12 @@ var OverlayManager = {
       } else if (this.overlays[name]) {
         throw new Error('The overlay is already registered.');
       }
-      this.overlays[name] = { element: element,
-                              container: container,
-                              callerCloseMethod: (callerCloseMethod || null),
-                              canForceClose: (canForceClose || false) };
+      this.overlays[name] = {
+        element,
+        container,
+        callerCloseMethod: (callerCloseMethod || null),
+        canForceClose: (canForceClose || false),
+      };
       resolve();
     }.bind(this));
   },