Cleanups.

runtime/lib/array_patch.dart

Index: runtime/lib/array_patch.dart
===================================================================
--- runtime/lib/array_patch.dart	(revision 16730)
+++ runtime/lib/array_patch.dart	(working copy)
@@ -7,7 +7,7 @@
 // fixed size array.
 patch class List<E> {
   /* patch */ factory List([int length = 0]) {
-    if (length is! int || length < 0) {
+    if ((length is! int) || (length < 0)) {
       throw new ArgumentError("Length must be a positive integer: $length.");
     }
     _GrowableObjectArray<E> result = new _GrowableObjectArray<E>();
@@ -16,7 +16,7 @@
   }
 
   /* patch */ factory List.fixedLength(int length, {E fill: null}) {
-    if (length is! int || length < 0) {
+    if ((length is! int) || (length < 0)) {
       throw new ArgumentError("Length must be a positive integer: $length.");
     }
     _ObjectArray<E> result = new _ObjectArray<E>(length);
@@ -29,17 +29,15 @@
   }
 
   /* patch */ factory List.filled(int length, E fill) {
-    if (length is! int || length < 0) {
+    if ((length is! int) || (length < 0)) {
       throw new ArgumentError("Length must be a positive integer: $length.");
     }
     _GrowableObjectArray<E> result =
         new _GrowableObjectArray<E>.withCapacity(length < 4 ? 4 : length);
-    if (length != 0) {
-      result.length = length;
-      if (fill != null) {
-        for (int i = 0; i < length; i++) {
-          result[i] = fill;
-        }
+    result.length = length;
+    if (fill != null) {
+      for (int i = 0; i < length; i++) {
+        result[i] = fill;
       }
     }
     return result;