Bug 630838 - Clear document.popupNode between browser chrome tests.

r=mano, gavin a=tests-only

testing/mochitest/browser-test.js

@@ -169,6 +169,11 @@ Tester.prototype = {
         }
       };
 
+      // Clear document.popupNode.  The test could have set it to a custom value
+      // for its own purposes, nulling it out it will go back to the default
+      // behavior of returning the last opened popup.
+      document.popupNode = null;
+
       // Note the test run time
       let time = Date.now() - this.lastStartTime;
       this.dumper.dump("INFO TEST-END | " + this.currentTest.path + " | finished in " + time + "ms\n");

testing/mochitest/tests/browser/Makefile.in

@@ -50,6 +50,8 @@ _BROWSER_TEST_FILES = \
 	                  browser_pass.js \
 	                  browser_async.js \
 	                  browser_privileges.js \
+	                  browser_popupNode.js \
+	                  browser_popupNode_check.js \
 # Disabled, these are only good for testing the harness' failure reporting
 #	                  browser_zz_fail_openwindow.js \
 #	                  browser_fail.js \

testing/mochitest/tests/browser/browser_popupNode.js

@@ -0,0 +1,4 @@
+function test() {
+  document.popupNode = document;
+  isnot(document.popupNode, null, "document.popupNode has been correctly set");
+}

testing/mochitest/tests/browser/browser_popupNode_check.js

@@ -0,0 +1,3 @@
+function test() {
+  is(document.popupNode, null, "document.popupNode has been correctly cleared");
+}