Implement parsing support for generic functions

tests/language/language.status

 # Copyright (c) 2012, 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 directory contains tests that are intended to show the
 # current state of the language.
 
 [ ($compiler == none || $compiler == precompiler || $compiler == dart2app || $compiler == dart2appjit) ]
 tearoff_constructor_basic_test: Skip # Crashes in checked mode -- hausner investigating
 
@@ skipping 27 matching lines @@
 # Non-contractive types are not supported in the vm.
 cyclic_type_test/02: Fail, OK
 cyclic_type_test/04: Fail, OK
 cyclic_type2_test: Fail, OK
 least_upper_bound_expansive_test/*: Fail, OK
 
 async_star_regression_2238_test: CompileTimeError, RuntimeError # drt only runtime-errs.
 async_star_cancel_while_paused_test: RuntimeError
 
 # Experimental feature: Syntactic support for generic methods.
-generic_methods_test: CompiletimeError # Issue 25869
-generic_functions_test: CompiletimeError # Issue 25869
-generic_local_functions_test: CompiletimeError # Issue 25869
-generic_sends_test: CompiletimeError # Issue 25869
-generic_methods_new_test: CompiletimeError # Issue 25869
-generic_methods_function_type_test: CompiletimeError # Issue 25869
-generic_methods_type_expression_test: CompiletimeError # Issue 25869
+generic_methods_type_expression_test: RuntimeError # Issue 25869
+
+[ ($compiler == none || $compiler == precompiler || $compiler == dart2app || $compiler == dart2appjit) && $checked ]
+# The generic functions tests fail in checked mode because the parsed type parameters
+# are ignored.
+generic_methods_function_type_test: RuntimeError # Issue 25869
+generic_methods_test: RuntimeError # Issue 25869
+generic_methods_new_test: RuntimeError # Issue 25869
+generic_local_functions_test: RuntimeError # Issue 25869
+generic_functions_test: RuntimeError # Issue 25869
 
 [ ($compiler == none || $compiler == precompiler || $compiler == dart2app || $compiler == dart2appjit) && ($runtime == vm || $runtime == dart_precompiled || $runtime == dart_app) ]
 
 class_keyword_test/02: MissingCompileTimeError # Issue 13627
 unicode_bom_test: Fail # Issue 16067
 vm/debug_break_enabled_vm_test/01: Crash, OK # Expected to hit breakpoint.
 try_catch_optimized1_test: Skip # Srdjan investigating
 
 [ ($compiler == none || $compiler == precompiler || $compiler == dart2app || $compiler == dart2appjit) && $checked ]
 type_variable_bounds4_test/01: Fail # Issue 14006
@@ skipping 28 matching lines @@
 mirror_in_static_init_test: Fail # Issue 22071
 vm/debug_break_enabled_vm_test/*: Skip # Issue 14651.
 
 # These tests need the flag --initializing-formal-access to pass:
 initializing_formal_access_test: Skip
 initializing_formal_capture_test: Skip
 initializing_formal_final_test: Skip
 initializing_formal_type_test: Skip
 
 # Experimental feature: Syntactic support for generic methods.
-generic_methods_test: RuntimeError # Issue 25869
-generic_functions_test: RuntimeError # Issue 25869
-generic_local_functions_test: RuntimeError # Issue 25869
-generic_sends_test: RuntimeError # Issue 25869
-generic_methods_new_test: RuntimeError # Issue 25869
-generic_methods_function_type_test: RuntimeError # Issue 25869
-generic_methods_type_expression_test: RuntimeError # Issue 25869
+# Skip these in dartium, because the test framework can't pass VM flags to
+generic_methods_test: Skip # Issue 25869
+generic_functions_test: Skip # Issue 25869
+generic_local_functions_test: Skip # Issue 25869
+generic_sends_test: Skip # Issue 25869
+generic_methods_new_test: Skip # Issue 25869
+generic_methods_function_type_test: Skip # Issue 25869
+generic_methods_type_expression_test: Skip # Issue 25869
 
 config_import_test: Skip  # Issue 26250
 
 [ $compiler == none && $runtime == dartium && $system == linux && $arch != x64 ]
 issue_22780_test/01: Pass, Timeout # Issue 24473
 
 [ $compiler == none && $runtime == dartium && $system == linux && $arch == x64 ]
 async_await_test: Skip # Issue 26198
 
 [ $compiler == none && $runtime == drt ]
@@ skipping 147 matching lines @@
 deferred_regression_22995_test: Crash # Requires deferred libraries
 deferred_shadow_load_library_test: Crash # Requires deferred libraries
 deferred_shared_and_unshared_classes_test: Crash # Requires deferred libraries
 deferred_static_seperate_test: Crash # Requires deferred libraries
 deferred_super_dependency_test: Pass, Crash # Requires deferred libraries
 deferred_type_dependency_test: Crash # Requires deferred libraries
 issue_1751477_test: Crash # Requires deferred libraries
 regress_23408_test: Crash # Requires deferred libraries
 regress_22443_test: Crash # Requires deferred libraries
 tearoff_basic_test: Crash # Requires deferred libraries