[tests] Cleanup tests that use assertOptimized()/assertUnoptimized().

test/mjsunit/field-type-tracking.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --allow-natives-syntax --nostress-opt --track-field-types
+// Flags: --crankshaft --no-always-opt
 
 (function() {
   var o = { text: "Hello World!" };
   function A() {
     this.a = o;
   }
   function readA(x) {
     return x.a;
   }
   var a = new A();
@@ skipping 142 matching lines @@
   assertEquals(readA(b), 2);
   assertEquals(readA(f), 1);
   assertEquals(readA(b), 2);
   %OptimizeFunctionOnNextCall(readA);
   assertEquals(readA(f), 1);
   assertEquals(readA(b), 2);
   assertOptimized(readA);
   f.a.y = 0;
   assertUnoptimized(readA);
 })();