MD WebUI: Fix incorrect positioning of action menu after window resize

ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js

Index: ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js
diff --git a/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js b/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js
index ba7728b168f7fa8aae778d703142d48e8f4643dd..24e54ba11419875e6fd2b8cfb423ebf602f8aed7 100644
--- a/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js
+++ b/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js
@@ -130,6 +130,11 @@ Polymer({
     }.bind(this);
     window.addEventListener('resize', this.onWindowResize_);
 
+    // Reset position to prevent previous values from affecting layout.
+    this.style.left = '';
+    this.style.right = '';
+    this.style.top = '';
+
     this.showModal();
 
     var rect = this.anchorElement_.getBoundingClientRect();

[dpapad, 2017/01/06 16:34:49]

I don't fully understand this fix. Per my own debugging at
https://bugs.chromium.org/p/chromium/issues/detail?id=667198#c2 (see video), the
getBoundingClientRect() call here returns the wrong values (clearly shown in the
video, unless I am mistaken). How is this affected by the previous values of
this.style.left/right/top? 

Are you 100% sure that this fixes the problem?

[dpapad, 2017/01/12 18:52:54]

Per explanation at
https://bugs.chromium.org/p/chromium/issues/detail?id=667198#c13, I know
understand how this fixes the issue. Thanks.