fix(Viewer): trigger resized on attach

Ensure components get notified on `canvas.resized`, whenever
the Viewer instance gets attached.

lib/Viewer.js

@@ -379,6 +379,8 @@ Viewer.prototype.attachTo = function(parentNode) {
   parentNode.appendChild(this._container);
 
   this._emit('attach', {});
+
+  this.get('canvas').resized();
 };
 
 Viewer.prototype.getDefinitions = function() {

test/spec/ViewerSpec.js

@@ -962,12 +962,20 @@ describe('Viewer', function() {
         // assume
         expect(viewer._container.parentNode).not.to.exist;
 
+        /* global sinon */
+        var resizedSpy = sinon.spy();
+
+        viewer.on('canvas.resized', resizedSpy);
+
         // when
         viewer.attachTo(container);
 
         // then
         expect(viewer._container.parentNode).to.equal(container);
 
+        // should trigger resized
+        expect(resizedSpy).to.have.been.called;
+
         done(err, warnings);
       });
     });