Add type inference for while and do 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 304165bd5bc5dbaa6a5091a9872cab7ca21e9932..03611e7c5a061502c3cde692c81016f41d455cd9 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -2491,7 +2491,7 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
       body = new LabeledStatement(body);
       continueTarget.resolveContinues(body);
     }
-    Statement result = new DoStatement(body, condition);
+    Statement result = new KernelDoStatement(body, condition);
     if (breakTarget.hasUsers) {
       result = new LabeledStatement(result);
       breakTarget.resolveBreaks(result);
@@ -2637,7 +2637,7 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
       body = new LabeledStatement(body);
       continueTarget.resolveContinues(body);
     }
-    Statement result = new WhileStatement(condition, body);
+    Statement result = new KernelWhileStatement(condition, body);
     if (breakTarget.hasUsers) {
       result = new LabeledStatement(result);
       breakTarget.resolveBreaks(result);