Support intercepted getters, setters and index operations.

tests/compiler/dart2js/js_backend_cps_ir_interceptors_test.dart

Index: tests/compiler/dart2js/js_backend_cps_ir_interceptors_test.dart
diff --git a/tests/compiler/dart2js/js_backend_cps_ir_interceptors_test.dart b/tests/compiler/dart2js/js_backend_cps_ir_interceptors_test.dart
index ef56ac0342b592dce9223fcaee0d7560871133d7..da5691842a168afdc17a4ac0424d338c02d1cc21 100644
--- a/tests/compiler/dart2js/js_backend_cps_ir_interceptors_test.dart
+++ b/tests/compiler/dart2js/js_backend_cps_ir_interceptors_test.dart
@@ -22,9 +22,48 @@ function() {
   var g, v0;
   g = 1;
   v0 = 3;
-  P.print(J.getInterceptor(g).$add(g, v0));
+  P.print(J.getInterceptor$ns(g).$add(g, v0));
   return null;
 }"""),
+  const TestEntry("""
+main() {
+  var l = ['hest', ['h', 'e', 's', 't']];
+  print(l.length);
+  for (int i  = 0; i < l.length; i++) {
+    var x = l[i];
+    for (int j = 0; j < x.length; j++) {
+      print(x[j]);
+    }
+  }
+}""",
+r"""
+function() {
+  var l, i, v0, x, j, v1, v2, v3;
+  l = ["hest", ["h", "e", "s", "t"]];
+  P.print(J.getInterceptor$as(l).get$length(l));
+  i = 0;
+  L0:
+    while (true) {
+      v0 = J.getInterceptor$as(l).get$length(l);
+      if (P.identical(J.getInterceptor$n(i).$lt(i, v0), true)) {
+        x = J.getInterceptor$as(l).$index(l, i);
+        j = 0;
+        while (true) {
+          v1 = J.getInterceptor$as(x).get$length(x);
+          if (P.identical(J.getInterceptor$n(j).$lt(j, v1), true)) {
+            P.print(J.getInterceptor$as(x).$index(x, j));
+            v2 = 1;
+            j = J.getInterceptor$ns(j).$add(j, v2);
+          } else {
+            v3 = 1;
+            i = J.getInterceptor$ns(i).$add(i, v3);
+            continue L0;
+          }
+        }
+      } else
+        return null;
+    }
+}"""),
 ];