cps-ir: Remove redundant identical() calls in type propagation.

tests/compiler/dart2js/js_backend_cps_ir_control_flow_test.dart

 // Copyright (c) 2014, 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 of control flow statements.
 
 library control_flow_tests;
 
 import 'js_backend_cps_ir.dart';
 
@@ skipping 19 matching lines @@
       print(1);
     }
     print(2);
   }
 }
 """, """
 function() {
   L0:
     while (true)
       while (true) {
-        while (P.identical(V.foo(true), true))
-          if (P.identical(V.foo(false), true)) {
+        while (V.foo(true))
+          if (V.foo(false)) {
             P.print(2);
             continue L0;
           }
         P.print(1);
       }
 }"""),
   const TestEntry("""
 foo(a) => a;
 
 main() {
@@ skipping 21 matching lines @@
 
 main() {
  if (foo(true)) {
    print(1);
  } else {
    print(2);
  }
  print(3);
 }""", """
 function() {
-  P.identical(V.foo(true), true) ? P.print(1) : P.print(2);
+  V.foo(true) ? P.print(1) : P.print(2);
   P.print(3);
   return null;
 }"""),
 const TestEntry("""
 foo(a) => a;
 
 main() {
  if (foo(true)) {
    print(1);
    print(1);
  } else {
    print(2);
    print(2);
  }
  print(3);
 }""", """
 function() {
-  if (P.identical(V.foo(true), true)) {
+  if (V.foo(true)) {
     P.print(1);
     P.print(1);
   } else {
     P.print(2);
     P.print(2);
   }
   P.print(3);
   return null;
 }"""),
 const TestEntry("""
@@ skipping 19 matching lines @@
 }""","""
 function() {
   P.identical(V.foo(), true) ? P.print("bad") : P.print("good");
   return null;
 }"""),
 ];
 
 void main() {
   runTests(tests);
 }