dart2js cps: Do not inline string interpolation helper.

tests/compiler/dart2js/cps_ir/expected/constructor_8.js

 // Expectation for test: 
 // class C<T> {
 //   foo() => C;
 // }
 // main() {
 //   print(new C<int>().foo());
 // }
 
 function() {
-  var line;
+  var v0 = C.Type_C_cdS, v1;
   V.C$();
-  line = H.S(C.Type_C_cdS);
+  v1 = H.S((v1 = v0._unmangledName) == null ? v0._unmangledName = function(str, names) {
+    return str.replace(/[^<,> ]+/g, function(m) {
+      return names[m] || m;
+    });
+  }(v0._typeName, init.mangledGlobalNames) : v1);
   if (typeof dartPrint == "function")
-    dartPrint(line);
+    dartPrint(v1);
   else if (typeof console == "object" && typeof console.log != "undefined")
-    console.log(line);
+    console.log(v1);
   else if (!(typeof window == "object")) {
     if (!(typeof print == "function"))
-      throw "Unable to print message: " + String(line);
-    print(line);
+      throw "Unable to print message: " + String(v1);
+    print(v1);
   }
 }