BREAKING - Fix sizing of container with child overflowing parent

Summary:
Fixes issue brought up in https://github.com/facebook/react-native/issues/10603

The gist of the problem is that in css it is fine for a child to overflow a parent if it feels the need to, we were not respecting this.

Reviewed By: gkassabli

Differential Revision: D4157971

fbshipit-source-id: 3cfae15ac8b65b70f01789444099ee684e1b099a

gentest/fixtures/CSSSizeOverflowTest.html

@@ -0,0 +1,11 @@
+<div id="nested_overflowing_child" style="height: 100px; width: 100px;">
+  <div>
+    <div style="height: 200px; width: 200px;"></div>
+  </div>
+</div>
+
+<div id="nested_overflowing_child_in_constraint_parent" style="height: 100px; width: 100px;">
+  <div style="height: 100px; width: 100px;">
+    <div style="height: 200px; width: 200px;"></div>
+  </div>
+</div>