Fix type inference of assignments to local variables.

pkg/front_end/test/fasta/strong.status

 # 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.md file.
 
 # Status file for the strong_test.dart test suite. This is testing generating
 # Kernel ASTs directly, that is, code in pkg/fasta/lib/src/kernel/ with
 # strong-mode enabled.
 
 DeltaBlue: Fail
 accessors: Fail
@@ skipping 38 matching lines @@
 store_load: Fail
 stringliteral: Fail
 super_rasta_copy: Fail
 top_level_accessors: Fail
 type_variable_as_super: Fail
 typedef: Fail
 uninitialized_fields: Fail
 unused_methods: Fail
 void-methods: Fail
 
-inference/block_bodied_lambdas_downwards_incompatible_with_upwards_inference: Fail
-inference/block_bodied_lambdas_infer_bottom_sync: Fail
 inference/block_bodied_lambdas_sync_star: Fail
 inference/circular_reference_via_closures: Fail
 inference/circular_reference_via_closures_initializer_types: Fail
 inference/constructors_infer_from_arguments: Fail
 inference/constructors_infer_from_arguments_const: Fail
 inference/constructors_infer_from_arguments_const_with_upper_bound: Fail
 inference/constructors_infer_from_arguments_factory: Fail
 inference/constructors_infer_from_arguments_factory_calls_constructor: Fail
 inference/constructors_infer_from_arguments_named_factory: Fail
 inference/constructors_infer_from_arguments_redirecting: Fail
@@ skipping 190 matching lines @@
 rasta/this_invoke: Fail
 rasta/try_label: Fail
 rasta/type_literals: VerificationError
 rasta/type_with_parse_error: Fail
 rasta/typedef: VerificationError
 rasta/unresolved: Fail
 rasta/unresolved_constructor: Fail
 rasta/unresolved_for_in: Fail
 rasta/unresolved_recovery: Fail
 rasta/unsupported_platform_library: Fail