cleanup: Port non-GObject classes to JS6 classes

ES6 finally adds standard class syntax to the language, so we can
replace our custom Lang.Class framework with the new syntax. Any
classes that inherit from GObject will need special treatment,
so limit the port to regular javascript classes for now.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/361

js/ui/grabHelper.js

@@ -2,7 +2,6 @@
 
 const Clutter = imports.gi.Clutter;
 const Gtk = imports.gi.Gtk;
-const Lang = imports.lang;
 const Meta = imports.gi.Meta;
 const Shell = imports.gi.Shell;
 const St = imports.gi.St;
@@ -46,10 +45,8 @@ function _popGrabHelper(grabHelper) {
 // your code just needs to deal with it; you shouldn't adjust behavior directly
 // after you call ungrab(), but instead pass an 'onUngrab' callback when you
 // call grab().
-var GrabHelper = new Lang.Class({
-    Name: 'GrabHelper',
-
-    _init(owner, params) {
+var GrabHelper = class GrabHelper {
+    constructor(owner, params) {
         this._owner = owner;
         this._modalParams = params;
 
@@ -59,7 +56,7 @@ var GrabHelper = new Lang.Class({
         this._ignoreUntilRelease = false;
 
         this._modalCount = 0;
-    },
+    }
 
     // addActor:
     // @actor: an actor
@@ -71,7 +68,7 @@ var GrabHelper = new Lang.Class({
             this.removeActor(actor);
         });
         this._actors.push(actor);
-    },
+    }
 
     // removeActor:
     // @actor: an actor
@@ -86,7 +83,7 @@ var GrabHelper = new Lang.Class({
             actor.disconnect(actor.__grabHelperDestroyId);
             delete actor.__grabHelperDestroyId;
         }
-    },
+    }
 
     _isWithinGrabbedActor(actor) {
         let currentActor = this.currentGrab.actor;
@@ -98,19 +95,19 @@ var GrabHelper = new Lang.Class({
             actor = actor.get_parent();
         }
         return false;
-    },
+    }
 
     get currentGrab() {
         return this._grabStack[this._grabStack.length - 1] || {};
-    },
+    }
 
     get grabbed() {
         return this._grabStack.length > 0;
-    },
+    }
 
     get grabStack() {
         return this._grabStack;
-    },
+    }
 
     _findStackIndex(actor) {
         if (!actor)
@@ -121,7 +118,7 @@ var GrabHelper = new Lang.Class({
                 return i;
         }
         return -1;
-    },
+    }
 
     _actorInGrabStack(actor) {
         while (actor) {
@@ -131,11 +128,11 @@ var GrabHelper = new Lang.Class({
             actor = actor.get_parent();
         }
         return -1;
-    },
+    }
 
     isActorGrabbed(actor) {
         return this._findStackIndex(actor) >= 0;
-    },
+    }
 
     // grab:
     // @params: A bunch of parameters, see below
@@ -195,7 +192,7 @@ var GrabHelper = new Lang.Class({
         }
 
         return true;
-    },
+    }
 
     _takeModalGrab() {
         let firstGrab = (this._modalCount == 0);
@@ -208,7 +205,7 @@ var GrabHelper = new Lang.Class({
 
         this._modalCount++;
         return true;
-    },
+    }
 
     _releaseModalGrab() {
         this._modalCount--;
@@ -221,7 +218,7 @@ var GrabHelper = new Lang.Class({
 
         Main.popModal(this._owner);
         global.sync_pointer();
-    },
+    }
 
     // ignoreRelease:
     //
@@ -231,7 +228,7 @@ var GrabHelper = new Lang.Class({
     // the next release event.
     ignoreRelease() {
         this._ignoreUntilRelease = true;
-    },
+    }
 
     // ungrab:
     // @params: The parameters for the grab; see below.
@@ -274,7 +271,7 @@ var GrabHelper = new Lang.Class({
             if (poppedGrab.savedFocus)
                 poppedGrab.savedFocus.grab_key_focus();
         }
-    },
+    }
 
     onCapturedEvent(event) {
         let type = event.type();
@@ -322,5 +319,5 @@ var GrabHelper = new Lang.Class({
         }
 
         return Clutter.EVENT_STOP;
-    },
-});
+    }
+};