Implement cascaded calls.

lib/compiler/implementation/ssa/builder.dart

Index: lib/compiler/implementation/ssa/builder.dart
diff --git a/lib/compiler/implementation/ssa/builder.dart b/lib/compiler/implementation/ssa/builder.dart
index 995a244337dc3cad8ea58310f6310e68baae0a87..367c719fafb73fcf2df7c61c3cbe9d4a28038275 100644
--- a/lib/compiler/implementation/ssa/builder.dart
+++ b/lib/compiler/implementation/ssa/builder.dart
@@ -1019,6 +1019,10 @@ class SsaBuilder implements Visitor {
     return stack.removeLast();
   }
 
+  void dup() {
+    stack.add(stack.last());
+  }
+
   HBoolify popBoolified() {
     HBoolify boolified = new HBoolify(pop());
     add(boolified);
@@ -2298,6 +2302,17 @@ class SsaBuilder implements Visitor {
     unreachable();
   }
 
+  visitCascade(Cascade node) {
+    visit(node.expression);
+    // Remove the result and reveal the duplicated receiver on the stack.
+    pop();
+  }
+
+  visitCascadeReceiver(CascadeReceiver node) {
+    visit(node.expression);
+    dup();
+  }
+
   visitReturn(Return node) {
     HInstruction value;
     if (node.expression === null) {