#97: Also check for attribute handlers through their lowercase name

IE automatically lowercases all attribute names when doctype is HTML. This is a small bandaid to
fix setAttribute for fields like fieldOfView in IE until we normalize all attribute names to be lowercase.

src/interface/elements.js

@@ -131,7 +131,7 @@ function handleAttributeChanged(mutation) {
     if (!elementHandler) {
         return;
     }
-    var attributeHandler = elementHandler.handlers[mutation.attributeName];
+    var attributeHandler = elementHandler.handlers[mutation.attributeName] || elementHandler.handlers[mutation.attributeName.toLowerCase()];
     if (!attributeHandler) {
         return;
     }