Prefer window.getSelection for IE

IE9+ supports `window.getSelection()` but `SelectEventPlugin` gives precedence to `document.selection` instead. `document.selection` is still available in later versions of IE, but the modern Selection object is preferable. Swap the two.

src/browser/eventPlugins/SelectEventPlugin.js

@@ -69,6 +69,14 @@ function getSelection(node) {
       start: node.selectionStart,
       end: node.selectionEnd
     };
+  } else if (window.getSelection) {
+    var selection = window.getSelection();
+    return {
+      anchorNode: selection.anchorNode,
+      anchorOffset: selection.anchorOffset,
+      focusNode: selection.focusNode,
+      focusOffset: selection.focusOffset
+    };
   } else if (document.selection) {
     var range = document.selection.createRange();
     return {
@@ -77,14 +85,6 @@ function getSelection(node) {
       top: range.boundingTop,
       left: range.boundingLeft
     };
-  } else {
-    var selection = window.getSelection();
-    return {
-      anchorNode: selection.anchorNode,
-      anchorOffset: selection.anchorOffset,
-      focusNode: selection.focusNode,
-      focusOffset: selection.focusOffset
-    };
   }
 }