[fix] onLayout calculation

The 0.0.69 release introduced a regression in UIManager's measurement
calculations.

Using `offset` properties returns the offset relative to the closest
positioned ancestor. Make `getRect` iterate over the ancestor chain.

Fix #341
Close #345

src/apis/UIManager/index.js

@@ -3,9 +3,14 @@ import CSSPropertyOperations from 'react-dom/lib/CSSPropertyOperations';
 
 const getRect = (node) => {
   const height = node.offsetHeight;
-  const left = node.offsetLeft;
-  const top = node.offsetTop;
   const width = node.offsetWidth;
+  let left = 0;
+  let top = 0;
+  while (node && node.nodeType === 1 /* Node.ELEMENT_NODE */) {
+    left += node.offsetLeft;
+    top += node.offsetTop;
+    node = node.offsetParent;
+  }
   return { height, left, top, width };
 };