Minor JSTypeRegistry cleanup

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=133434527

src/com/google/javascript/rhino/Node.java

@@ -1611,6 +1611,16 @@ public boolean hasOneChild() {
     return first != null && first.next == null;
   }
 
+  /**
+   * Check for zero or one child more efficiently than by iterating over all the
+   * children as is done with Node.getChildCount().
+   *
+   * @return Whether the node has no children or exactly one child.
+   */
+  public boolean hasZeroOrOneChild() {
+    return first == getLastChild();
+  }
+
   /**
    * Check for more than one child more efficiently than by iterating over all
    * the children as is done with Node.getChildCount().

src/com/google/javascript/rhino/jstype/JSTypeRegistry.java

@@ -1656,30 +1656,28 @@ private JSType createFromTypeNodesInternal(Node n, String sourceName,
       // TODO(martinprobst): The new type syntax resolution should be separate.
       // Remove the NAME case then.
       case NAME:
-        JSType namedType = getType(scope, n.getString(), sourceName,
-            n.getLineno(), n.getCharno());
-        if ((namedType instanceof ObjectType) &&
-            !(namedType instanceof NamespaceType) &&
-            !(nonNullableTypeNames.contains(n.getString()))) {
+        JSType namedType = getType(scope, n.getString(), sourceName, n.getLineno(), n.getCharno());
+        if ((namedType instanceof ObjectType)
+            && !(namedType instanceof NamespaceType)
+            && !(nonNullableTypeNames.contains(n.getString()))) {
           Node typeList = n.getFirstChild();
-          int nAllowedTypes = namedType.getTemplateTypeMap().numUnfilledTemplateKeys();
           if (!namedType.isUnknownType() && typeList != null) {
             // Templatized types.
-            ImmutableList.Builder<JSType> templateTypes =
-                ImmutableList.builder();
+            ImmutableList.Builder<JSType> templateTypes = ImmutableList.builder();
 
-            // Special case for Object, where Object.<X> implies Object.<?,X>.
+            // Special case for Object, where Object<X> implies Object<?,X>.
             if ((n.getString().equals("Object") || n.getString().equals("window.Object"))
-                && typeList.getFirstChild() == typeList.getLastChild()) {
+                && typeList.hasZeroOrOneChild()) {
               templateTypes.add(getNativeType(UNKNOWN_TYPE));
             }
 
+            int nAllowedTypes = namedType.getTemplateTypeMap().numUnfilledTemplateKeys();
             int templateNodeIndex = 0;
-            for (Node templateNode : typeList.getFirstChild().siblings()) {
+            for (Node templateNode : typeList.children()) {
               // Don't parse more templatized type nodes than the type can
               // accommodate. This is because some existing clients have
               // template annotations on non-templatized classes, for instance:
-              //   goog.structs.Set.<SomeType>
+              //   goog.structs.Set<SomeType>
               // The problem in these cases is that the previously-unparsed
               // SomeType is not actually a valid type. To prevent these clients
               // from seeing unknown type errors, we explicitly don't parse
@@ -1692,11 +1690,9 @@ private JSType createFromTypeNodesInternal(Node n, String sourceName,
                     sourceName, templateNode.getLineno(), templateNode.getCharno());
                 break;
               }
-              templateTypes.add(createFromTypeNodesInternal(
-                  templateNode, sourceName, scope));
+              templateTypes.add(createFromTypeNodesInternal(templateNode, sourceName, scope));
             }
-            namedType = createTemplatizedType(
-                (ObjectType) namedType, templateTypes.build());
+            namedType = createTemplatizedType((ObjectType) namedType, templateTypes.build());
             Preconditions.checkNotNull(namedType);
           }
           return createDefaultObjectUnion(namedType);