Bug 748490 - Part 3: Followups to part 2; r=ted

Previous patch was submitted prematurely by accident. This addresses
nits from review.

config/rules.mk

@@ -117,7 +117,7 @@ xpcshell-tests:
 	  --symbols-path=$(DIST)/crashreporter-symbols \
 	  --build-info-json=$(DEPTH)/mozinfo.json \
 	  --tests-root-dir=$(testxpcobjdir) \
-	  --tests-modules-dir=$(DEPTH)/_tests/modules \
+	  --testing-modules-dir=$(DEPTH)/_tests/modules \
 	  --xunit-file=$(testxpcobjdir)/$(relativesrcdir)/results.xml \
 	  --xunit-suite-name=xpcshell \
 	  $(EXTRA_TEST_ARGS) \
@@ -148,7 +148,7 @@ check-interactive:
 	  --symbols-path=$(DIST)/crashreporter-symbols \
 	  --build-info-json=$(DEPTH)/mozinfo.json \
 	  --test-path=$(SOLO_FILE) \
-	  --tests-modules-dir=$(DEPTH)/_tests/modules \
+	  --testing-modules-dir=$(DEPTH)/_tests/modules \
 	  --profile-name=$(MOZ_APP_NAME) \
 	  --interactive \
 	  $(LIBXUL_DIST)/bin/xpcshell \
@@ -162,7 +162,7 @@ check-one:
 	  --symbols-path=$(DIST)/crashreporter-symbols \
 	  --build-info-json=$(DEPTH)/mozinfo.json \
 	  --test-path=$(SOLO_FILE) \
-	  --tests-modules-dir=$(DEPTH)/_tests/modules \
+	  --testing-modules-dir=$(DEPTH)/_tests/modules \
 	  --profile-name=$(MOZ_APP_NAME) \
 	  --verbose \
 	  $(EXTRA_TEST_ARGS) \

js/src/config/rules.mk

@@ -117,7 +117,7 @@ xpcshell-tests:
 	  --symbols-path=$(DIST)/crashreporter-symbols \
 	  --build-info-json=$(DEPTH)/mozinfo.json \
 	  --tests-root-dir=$(testxpcobjdir) \
-	  --tests-modules-dir=$(DEPTH)/_tests/modules \
+	  --testing-modules-dir=$(DEPTH)/_tests/modules \
 	  --xunit-file=$(testxpcobjdir)/$(relativesrcdir)/results.xml \
 	  --xunit-suite-name=xpcshell \
 	  $(EXTRA_TEST_ARGS) \
@@ -148,7 +148,7 @@ check-interactive:
 	  --symbols-path=$(DIST)/crashreporter-symbols \
 	  --build-info-json=$(DEPTH)/mozinfo.json \
 	  --test-path=$(SOLO_FILE) \
-	  --tests-modules-dir=$(DEPTH)/_tests/modules \
+	  --testing-modules-dir=$(DEPTH)/_tests/modules \
 	  --profile-name=$(MOZ_APP_NAME) \
 	  --interactive \
 	  $(LIBXUL_DIST)/bin/xpcshell \
@@ -162,7 +162,7 @@ check-one:
 	  --symbols-path=$(DIST)/crashreporter-symbols \
 	  --build-info-json=$(DEPTH)/mozinfo.json \
 	  --test-path=$(SOLO_FILE) \
-	  --tests-modules-dir=$(DEPTH)/_tests/modules \
+	  --testing-modules-dir=$(DEPTH)/_tests/modules \
 	  --profile-name=$(MOZ_APP_NAME) \
 	  --verbose \
 	  $(EXTRA_TEST_ARGS) \

testing/testsuite-targets.mk

@@ -245,7 +245,7 @@ xpcshell-tests:
 	  --build-info-json=$(DEPTH)/mozinfo.json \
 	  --no-logfiles \
 	  --tests-root-dir=$(call core_abspath,_tests/xpcshell) \
-	  --tests-modules-dir=$(call core_abspath,_tests/modules) \
+	  --testing-modules-dir=$(call core_abspath,_tests/modules) \
 	  --xunit-file=$(call core_abspath,_tests/xpcshell/results.xml) \
 	  --xunit-suite-name=xpcshell \
           $(SYMBOLS_PATH) \

testing/xpcshell/head.js

@@ -303,7 +303,7 @@ function do_get_idle() {
 
 function _execute_test() {
   // Map resource://test/ to current working directory and
-  // resource://testing/ to the shared test modules directory.
+  // resource://testing-common/ to the shared test modules directory.
   let (ios = Components.classes["@mozilla.org/network/io-service;1"]
              .getService(Components.interfaces.nsIIOService)) {
     let protocolHandler =
@@ -318,7 +318,7 @@ function _execute_test() {
       modulesFile.initWithPath(_TESTING_MODULES_DIR);
 
       let modulesURI = ios.newFileURI(modulesFile);
-      protocolHandler.setSubstitution("testing", modulesURI);
+      protocolHandler.setSubstitution("testing-common", modulesURI);
     }
   }
 

testing/xpcshell/runxpcshelltests.py

@@ -235,7 +235,7 @@ class XPCShellTests(object):
         '-e', 'const _HEAD_JS_PATH = "%s";' % self.headJSPath
     ]
 
-    if self.testingModulesDir is not None:
+    if self.testingModulesDir:
         self.xpcsCmd.extend([
             '-e',
             'const _TESTING_MODULES_DIR = "%s";' % self.testingModulesDir
@@ -621,7 +621,7 @@ class XPCShellTests(object):
             raise Exception("testsRootDir path does not exists: %s" %
                     testsRootDir)
 
-    if testingModulesDir is not None:
+    if testingModulesDir:
         if not os.path.isabs(testingModulesDir):
             testingModulesDir = os.path.abspath(testingModulesDir)
 
@@ -900,7 +900,7 @@ class XPCShellOptions(OptionParser):
     self.add_option("--tests-root-dir",
                     type="string", dest="testsRootDir", default=None,
                     help="absolute path to directory where all tests are located. this is typically $(objdir)/_tests")
-    self.add_option("--tests-modules-dir",
+    self.add_option("--testing-modules-dir",
                     dest="testingModulesDir", default=None,
                     help="Directory where testing modules are located.")
     self.add_option("--total-chunks",