[Layout] Consistent input behavior

Inputs now handle invalid input consistently for all fields

platform/features/layout/src/elements/ImageProxy.js

@@ -52,6 +52,8 @@ define(
             //Expose width and height properties for editing
             proxy.editWidth = new AccessorMutator(element, 'width', proxy.checkNumeric);
             proxy.editHeight = new AccessorMutator(element, 'height', proxy.checkNumeric);
+            proxy.editX = new AccessorMutator(element,'x',proxy.checkNumeric);
+            proxy.editY = new AccessorMutator(element,'y', proxy.checkNumeric);
 
             return proxy;
         }