Rename "parallel recompilation" to "concurrent recompilation".

test/mjsunit/mjsunit.js

Index: test/mjsunit/mjsunit.js
diff --git a/test/mjsunit/mjsunit.js b/test/mjsunit/mjsunit.js
index 83449cc1e692e8d0754e49ac8d4122ea39662186..129353730ce1a8a4f111651294fb1e6cb7dc8b55 100644
--- a/test/mjsunit/mjsunit.js
+++ b/test/mjsunit/mjsunit.js
@@ -100,7 +100,7 @@ var assertInstanceof;
 var assertUnreachable;
 
 // Assert that the function code is (not) optimized.  If "no sync" is passed
-// as second argument, we do not wait for the parallel optimization thread to
+// as second argument, we do not wait for the concurrent optimization thread to
 // finish when polling for optimization status.
 // Only works with --allow-natives-syntax.
 var assertOptimized;