[test] Remove bogus --crankshaft flag from a modules test.

The function being tested is forced to go through Turbofan anyway (since it references a module variable).

Adding --turbo explicitly just to make a check happy.

BUG=

Review-Url: https://codereview.chromium.org/2664393003
Cr-Commit-Position: refs/heads/master@{#42844}

test/mjsunit/modules-turbo.js → test/mjsunit/modules-turbo1.js

@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 // MODULE
-// Flags: --allow-natives-syntax --crankshaft
+// Flags: --allow-natives-syntax --turbo
 
 export let x = 0;
 function foo() { x++ };