Implement type inference for asserts in constructor initializers.

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

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// This file declares a "shadow hierarchy" of concrete classes which extend
 /// the kernel class hierarchy, adding methods and fields needed by the
 /// BodyBuilder.
 ///
 /// Instances of these classes may be created using the factory methods in
 /// `ast_factory.dart`.
@@ skipping 72 matching lines @@
       KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
     typeNeeded =
         inferrer.listener.asExpressionEnter(this, typeContext) || typeNeeded;
     inferrer.inferExpression(operand, null, false);
     var inferredType = typeNeeded ? type : null;
     inferrer.listener.asExpressionExit(this, inferredType);
     return inferredType;
   }
 }
 
+/// Concrete shadow object representing an assert initializer in kernel form.
+class KernelAssertInitializer extends LocalInitializer
+    implements KernelInitializer {
+  /// The assert statement performing the check
+  AssertStatement _statement;
+
+  KernelAssertInitializer(VariableDeclaration variable, this._statement)
+      : super(variable);
+
+  @override
+  void _inferInitializer(KernelTypeInferrer inferrer) {
+    inferrer.listener.assertInitializerEnter(this);
+    inferrer.inferStatement(_statement);
+    inferrer.listener.assertInitializerExit(this);
+  }
+}
+
 /// Concrete shadow object representing an assertion statement in kernel form.
 class KernelAssertStatement extends AssertStatement implements KernelStatement {
   KernelAssertStatement(Expression condition,
       {Expression message, int conditionStartOffset, int conditionEndOffset})
       : super(condition,
             message: message,
             conditionStartOffset: conditionStartOffset,
             conditionEndOffset: conditionEndOffset);
 
   @override
@@ skipping 2341 matching lines @@
   accept(v) => unsupported("accept", -1, null);
 
   accept1(v, arg) => unsupported("accept1", -1, null);
 
   getStaticType(types) => unsupported("getStaticType", -1, null);
 
   transformChildren(v) => unsupported("transformChildren", -1, null);
 
   visitChildren(v) => unsupported("visitChildren", -1, null);
 }