Speed up some mjsunit test cases and clean up test expectations for arm and mips.

test/mjsunit/regress/regress-490.js

Index: test/mjsunit/regress/regress-490.js
diff --git a/test/mjsunit/regress/regress-490.js b/test/mjsunit/regress/regress-490.js
index 8dd89591719ae3cdf35d616ff89f046c71847785..6ce89db2f0e4500579d1116447bf35e24c8e618b 100644
--- a/test/mjsunit/regress/regress-490.js
+++ b/test/mjsunit/regress/regress-490.js
@@ -42,6 +42,9 @@ for (var i = 0; i < 10; i++) {
   var  b = '';
   for (var j = 0; j < 10; j++) {
     b += '$1';
+
+    // TODO(machenbach): Do we need all these replacements? Wouldn't corner
+    // cases like smallest and biggest suffice?
     a.replace(/^(.*)/, b);
   }
   a += a;