Do not count invocations but usage of a function, i.e., increment a function's counter at IC calls …

tests/language/src/MathVMTest.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Tests that the VM does not crash on weird corner cases of class Math.
-// VMOptions=--optimization_invocation_threshold=100
+// VMOptions=--optimization_counter_threshold=100
 
 class FakeNumber {
   const FakeNumber();
   void toDouble() {}
 }
 
 class MathTest {
   static bool testParseInt(x) {
     try {
       Math.parseInt(x);  // Expects string.
@@ skipping 15 matching lines @@
   static void testMain() {
     Expect.equals(false, testParseInt(5));
     Expect.equals(false, testSqrt(const FakeNumber()));
   }
 }
 main() {
   for (int i = 0; i < 200; i++) {
     MathTest.testMain();
   }
 }