Add support for (unintercepted) method calls to the cps js emitter.

tests/compiler/dart2js/js_backend_cps_ir_basic.dart

Index: tests/compiler/dart2js/js_backend_cps_ir_basic.dart
diff --git a/tests/compiler/dart2js/js_backend_cps_ir_basic.dart b/tests/compiler/dart2js/js_backend_cps_ir_basic.dart
index 8eb401bd3cbb96c76d2a1442edf71e69c64ae7b7..1455f5b2b926e7562b9fe613ff58459b0f13f08b 100644
--- a/tests/compiler/dart2js/js_backend_cps_ir_basic.dart
+++ b/tests/compiler/dart2js/js_backend_cps_ir_basic.dart
@@ -74,7 +74,8 @@ main() { return foo(); }
 function() {
   return null;
 }"""),
-const TestEntry("""
+  // Constructor invocation
+  const TestEntry("""
 main() {
   print(new Set());
   print(new Set.from([1, 2, 3]));
@@ -84,4 +85,13 @@ function() {
   P.print(P.Set_Set$from([1, 2, 3]));
   return null;
 }"""),
+  // Method invocation
+  const TestEntry("""
+main() {
+  print(new DateTime.now().isBefore(new DateTime.now()));
+}""", r"""
+function() {
+  P.print(P.DateTime$now().isBefore$1(P.DateTime$now()));
+  return null;
+}"""),
 ];