Relaxes treatment of method type parameter in `as` expressions.

tests/language/language.status

Index: tests/language/language.status
diff --git a/tests/language/language.status b/tests/language/language.status
index de99e84cbb3b32a8020426f9da40fe3fc7408fd0..da6754c6920ab50c730ff2b8096abdd7b8d65573 100644
--- a/tests/language/language.status
+++ b/tests/language/language.status
@@ -50,6 +50,9 @@ 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
 
+# Fails because `as T` is an error rather than being treated like `as dynamic`.
+generic_methods_type_expression_test: RuntimeError # Issue 27460
+
 [ ($compiler == none || $compiler == precompiler || $compiler == dart2app || $compiler == dart2appjit) && $checked ]
 # The generic functions tests fail in checked mode because the parsed type parameters
 # are ignored.