Implement type inference for conventional for-loops.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

Index: pkg/front_end/lib/src/fasta/kernel/body_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 99f2340a4c1b29e52282b052513723bc81333277..f90c08dcbc0644e2ac10db8e6e7621d8a886b870 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -1510,7 +1510,8 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
       body = new LabeledStatement(body);
       continueTarget.resolveContinues(body);
     }
-    Statement result = new ForStatement(variables, condition, updates, body);
+    Statement result =
+        new KernelForStatement(variables, condition, updates, body);
     if (begin != null) {
       result = new Block(<Statement>[begin, result]);
     }