Use jasmine.undefined for all comparisons to the undefined value, since undefined itself may be redefined elsewhere

in app code.  Thanks to Charlie Meyer at UIUC for the suggestion.

src/base.js

@@ -12,6 +12,14 @@ jasmine.unimplementedMethod_ = function() {
   throw new Error("unimplemented method");
 };
 
+/**
+ * Use <code>jasmine.undefined</code> instead of <code>undefined</code>, since <code>undefined</code is just
+ * a plain old variable and may be redefined by somebody else.
+ * 
+ * @private
+ */
+jasmine.undefined = jasmine.___undefined___;
+
 /**
  * Default interval for event loop yields. Small values here may result in slow test running. Zero means no updates until all tests have completed.
  *