Add negation to single-identifier tests in status files.

tests/language/language.status

Index: tests/language/language.status
diff --git a/tests/language/language.status b/tests/language/language.status
index efa57092b677c0b9c37c3128eab565c198586c39..bb8a0b8a80dc539a20eede5e5d2c2cffcec82141 100644
--- a/tests/language/language.status
+++ b/tests/language/language.status
@@ -79,7 +79,7 @@ export_ambiguous_main_negative_test: Fail # Issue 14763
 [ ($compiler == none || $compiler == precompiler || $compiler == app_jit || $compiler == dartk || $compiler == dartkp) && (($runtime == vm || $runtime == dart_precompiled) || $runtime == drt || $runtime == dartium || $runtime == flutter) ]
 dynamic_prefix_core_test/none: Fail # Issue 12478
 
-[ $compiler == none && $runtime == dartium && $unchecked ]
+[ $compiler == none && $runtime == dartium && ! $checked ]
 assertion_test: Fail # Issue 14651.
 generic_test: Fail # Issue 14651.
 list_literal4_test: Fail # Issue 14651.
@@ -240,7 +240,7 @@ stacktrace_demangle_ctors_test: SkipByDesign # Names are not scrubbed.
 library_env_test/has_io_support: RuntimeError, OK
 library_env_test/has_no_html_support: RuntimeError, OK
 
-[ ($compiler == none || $compiler == precompiler || $compiler == app_jit) && $browser != true ]
+[ ($compiler == none || $compiler == precompiler || $compiler == app_jit) && ! $browser ]
 # The following tests are supposed to fail.
 library_env_test/has_html_support: RuntimeError, OK
 library_env_test/has_no_io_support: RuntimeError, OK
@@ -298,7 +298,7 @@ vm/optimized_stacktrace_test: Pass, Slow
 [$runtime != vm || $compiler != none]
 assert_initializer_test: SKIP  # not implemented yet, experiment is VM only.
 
-[$runtime == vm && $compiler == none && $unchecked]
+[$runtime == vm && $compiler == none && ! $checked]
 assert_initializer_test/*: MissingCompileTimeError, OK  # asserts shouldn't fail in unchecked mode.
 assert_initializer_test/none: pass