Allow multiple lines of custom flags in javascript tests.

test/mjsunit/testcfg.py

Index: test/mjsunit/testcfg.py
diff --git a/test/mjsunit/testcfg.py b/test/mjsunit/testcfg.py
index 87ed4fae8fb8c3fc394a09b1c7259a864f470755..5a2f31481edeb43d4130351bae600bb143b69c60 100644
--- a/test/mjsunit/testcfg.py
+++ b/test/mjsunit/testcfg.py
@@ -56,9 +56,9 @@ class MjsunitTestCase(test.TestCase):
 
   def GetVmCommand(self, source):
     result = self.config.context.GetVmCommand(self, self.mode)
-    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()
     return result
 
   def GetVmArguments(self, source):