Insert implicit downcasts in kernel strong mode.

tests/language_strong/language_strong_kernel.status

Index: tests/language_strong/language_strong_kernel.status
diff --git a/tests/language_strong/language_strong_kernel.status b/tests/language_strong/language_strong_kernel.status
index 30aff8b2f3c156e933d3ce8d159232e5bb973649..7858270062e38651340fe16a6a067af3b82b7383 100644
--- a/tests/language_strong/language_strong_kernel.status
+++ b/tests/language_strong/language_strong_kernel.status
@@ -3,6 +3,7 @@
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dartk && $runtime == vm ]
+arithmetic2_test: RuntimeError # Throws CastError instead of TypeError
 assertion_test: RuntimeError
 async_await_test/02: DartkCompileTimeError
 async_await_test/03: DartkCompileTimeError
@@ -23,6 +24,7 @@ asyncstar_yield_test: Timeout
 asyncstar_yieldstar_test: Timeout
 await_in_cascade_test: RuntimeError
 bad_raw_string_negative_test: Fail
+bool_test: RuntimeError # Throws CastError instead of TypeError
 cha_deopt1_test: RuntimeError
 cha_deopt2_test: RuntimeError
 cha_deopt3_test: RuntimeError
@@ -127,6 +129,7 @@ generic_field_mixin5_test: DartkCompileTimeError
 generic_inheritance_test: RuntimeError
 generic_tearoff_test: Crash
 getter_closure_execution_order_test: RuntimeError
+if_null_evaluation_order_test: Crash # VM does not support BottomType
 inferrer_closure_test: RuntimeError
 initializing_formal_final_test: RuntimeError
 instance_creation_in_function_annotation_test: RuntimeError
@@ -146,6 +149,7 @@ mixin_mixin5_test: RuntimeError
 mixin_mixin_bound2_test: RuntimeError
 mixin_mixin_bound_test: RuntimeError
 no_main_test/01: DartkCrash
+operator4_test: RuntimeError # Throws CastError instead of TypeError
 prefix10_negative_test: Fail
 prefix21_test: RuntimeError
 recursive_generic_test: RuntimeError
@@ -155,7 +159,9 @@ regress_22700_test: RuntimeError
 regress_r24720_test: RuntimeError
 reify_typevar_static_test/00: MissingCompileTimeError
 reify_typevar_test: RuntimeError
+setter_no_getter_test/01: Crash # VM does not support BottomType
 switch_try_catch_test: RuntimeError
 sync_generator3_test/test2: RuntimeError
+type_error_test: RuntimeError # Throws CastError instead of TypeError
 type_literal_test: RuntimeError
-type_parameter_literal_test: RuntimeError
+type_parameter_literal_test: RuntimeError