refactor($compile): simplify multi element directive check

Previously, we would check if an attribute indicates a multi-element
directive, now we only do this check if the attribute name actually
matches the multi-element name pattern.

Closes #12365

Author: jbedard

src/ng/compile.js

@@ -1240,6 +1240,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
               return template.replace(/\{\{/g, startSymbol).replace(/}}/g, endSymbol);
         },
         NG_ATTR_BINDING = /^ngAttr[A-Z]/;
+    var MULTI_ELEMENT_DIR_RE = /^(.+)Start$/;
 
     compile.$$addBindingInfo = debugInfoEnabled ? function $$addBindingInfo($element, binding) {
       var bindings = $element.data('$binding') || [];
@@ -1524,13 +1525,11 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
                 });
             }
 
-            var directiveNName = ngAttrName.replace(/(Start|End)$/, '');
-            if (directiveIsMultiElement(directiveNName)) {
-              if (ngAttrName === directiveNName + 'Start') {
-                attrStartName = name;
-                attrEndName = name.substr(0, name.length - 5) + 'end';
-                name = name.substr(0, name.length - 6);
-              }
+            var multiElementMatch = ngAttrName.match(MULTI_ELEMENT_DIR_RE);
+            if (multiElementMatch && directiveIsMultiElement(multiElementMatch[1])) {
+              attrStartName = name;
+              attrEndName = name.substr(0, name.length - 5) + 'end';
+              name = name.substr(0, name.length - 6);
             }
 
             nName = directiveNormalize(name.toLowerCase());