Allow multiple lines of custom flags in javascript tests.

test/message/testcfg.py

Index: test/message/testcfg.py
diff --git a/test/message/testcfg.py b/test/message/testcfg.py
index de46cd68a273aec8caaee3373a0ec337b608655c..9cb58264e0eb9717e6edbe749a1391e222469a68 100644
--- a/test/message/testcfg.py
+++ b/test/message/testcfg.py
@@ -81,9 +81,9 @@ class MessageTestCase(test.TestCase):
   def GetCommand(self):
     result = self.config.context.GetVmCommand(self, self.mode)
     source = open(self.file).read()
-    flags_match = FLAGS_PATTERN.search(source)
-    if flags_match:
-      result += flags_match.group(1).strip().split()
+    flags_match = re.findall(FLAGS_PATTERN, source)
+    for match in flags_match:
+      result += match.strip().split()
     result.append(self.file)
     return result