Implement type inference for asserts in constructor initializers.

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

Index: pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
index 6f0141ed8f84319321b11c79e0d8ab3476178610..6a8e9e1a2a1e003efe092bff44b5b1e78b72d489 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
@@ -90,6 +90,23 @@ class KernelAsExpression extends AsExpression implements KernelExpression {
   }
 }
 
+/// 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,