Add type annotations to prevent issues with planned Flow changes

Summary:
We're planning a fix in Flow (D24112595) that uncovers some existing errors that were
previously suppressed. Adding these annotations prevents them from surfacing during the
deploy of the fix.

Changelog: [Internal]

Reviewed By: dsainati1

Differential Revision: D24147994

fbshipit-source-id: fef59a9427da6db79d4824e39768dd5ad0a8d1a3

Libraries/StyleSheet/splitLayoutProps.js

@@ -49,8 +49,8 @@ function splitLayoutProps(
   const inner = {};
   const outer = {};
   if (props) {
-    Object.keys(props).forEach(k => {
-      const value: $ElementType<DangerouslyImpreciseStyle, typeof k> = props[k];
+    Object.keys(props).forEach((k: string) => {
+      const value = props[k];
       if (OUTER_PROPS[k]) {
         outer[k] = value;
       } else {