Add type inference of annotations.

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 b5c15b1689d10cc2272984a28c0ab08244401649..a03bce05389964355fae1c2106110d13dd46a564 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -446,6 +446,7 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
     pop(); // Modifiers.
     List annotations = pop();
     if (annotations != null) {
+      _typeInferrer.inferMetadata(annotations);

[ahe, 2017/06/28 07:39:49]

Can you move all these calls to endMetadataStar? And then remove finishMetadata?

[Paul Berry, 2017/06/28 12:15:59]

I could do that now, but it would not work in the long term.  Once we have
support for annotations on local variables and local functions (see
https://github.com/dart-lang/sdk/issues/30031 and
https://github.com/dart-lang/sdk/issues/30035), we will have to ensure that type
inference for local annotations happens during the type inference phase, so that
code like this will infer correctly:

  class Foo {
    const Foo(dynamic x);
  }
  void test() {
    const x = 0; // Infers as: const int x = 0;
    @Foo([x]) // Infers as: @Foo(<int>[x])
    int y;
  }

Leaving as is for now.  If you have strong feelings about this, let me know and
we can discuss.

       Field field = fields.first.target;
       // The first (and often only field) will not get a clone.
       annotations.forEach(field.addAnnotation);
@@ -589,6 +590,7 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
     KernelFunctionBuilder builder = member;
     builder.body = body;
     Member target = builder.target;
+    _typeInferrer.inferMetadata(annotations);
     for (Expression annotation in annotations ?? const []) {
       target.addAnnotation(annotation);
     }
@@ -615,6 +617,13 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
     }
   }
 
+  @override
+  List<Expression> finishMetadata() {
+    List<Expression> expressions = pop();
+    _typeInferrer.inferMetadata(expressions);
+    return expressions;
+  }
+
   void finishConstructor(
       KernelConstructorBuilder builder, AsyncMarker asyncModifier) {
     /// Quotes below are from [Dart Programming Language Specification, 4th