autosize: Remove unnecessary guard in plotAutoSize

* Commit 5df675a (fix demo/outside legend bug and null data autoscale
  bug) introduced a guard in plotAutoSize to avoid calling layoutStyles
  while autosize is set to 'initial'.

* Commit ee974d9 (autosizing in shareplots, autosize aspect ratio
  restrictions and ...) removed the call to layoutStyles but forgot to
  remove the guard.

* This commit removes the guard.

* Checked that all the jasmine and image tests still pass.

Author: n-riesco

src/plot_api/plot_api.js

@@ -2570,8 +2570,7 @@ function plotAutoSize(gd, aobj) {
     }
     // if there's no size change, update layout but
     // delete the autosize attr so we don't redraw
-    // but can't call layoutStyles for initial autosize
-    else if(fullLayout.autosize !== 'initial') {
+    else {
         delete(aobj.autosize);
         fullLayout.autosize = gd.layout.autosize = true;
     }