[PRISM] Enable more passing tests

spec/prism.mspec

@@ -5,9 +5,6 @@
 MSpec.register(:exclude, "Warning.[] returns default values for categories :deprecated and :experimental")
 
 ## Language
-MSpec.register(:exclude, "Hash literal expands an '**{}' or '**obj' element with the last key/value pair taking precedence")
-MSpec.register(:exclude, "Hash literal expands an '**{}' and warns when finding an additional duplicate key afterwards")
-MSpec.register(:exclude, "Hash literal merges multiple nested '**obj' in Hash literals")
 MSpec.register(:exclude, "Hash literal raises a SyntaxError at parse time when Symbol key with invalid bytes")
 MSpec.register(:exclude, "Hash literal raises a SyntaxError at parse time when Symbol key with invalid bytes and 'key: value' syntax used")
 MSpec.register(:exclude, "Regexps with encoding modifiers supports /e (EUC encoding) with interpolation")

test/.excludes-prism/TestM17N.rb

@@ -3,8 +3,5 @@ exclude(:test_dynamic_sjis_regexp, "https://github.com/ruby/prism/issues/2664")
 exclude(:test_dynamic_utf8_regexp, "https://github.com/ruby/prism/issues/2664")
 exclude(:test_regexp_ascii, "https://github.com/ruby/prism/issues/2664")
 exclude(:test_regexp_embed, "https://github.com/ruby/prism/issues/2664")
-exclude(:test_regexp_mixed_unicode, "unknown")
-exclude(:test_regexp_too_short_multibyte_character, "unknown")
-exclude(:test_regexp_unicode, "unknown")
 exclude(:test_regexp_usascii, "unknown")
 exclude(:test_string_mixed_unicode, "unknown")

test/.excludes-prism/TestSyntax.rb

@@ -22,7 +22,6 @@ exclude(:test_numbered_parameter, "unknown")
 exclude(:test_optional_self_reference, "unknown")
 exclude(:test_safe_call_in_massign_lhs, "unknown")
 exclude(:test_syntax_error_at_newline, "unknown")
-exclude(:test_unassignable, "unknown")
 exclude(:test_unexpected_fraction, "unknown")
 exclude(:test_unterminated_heredoc_cr, "unknown")
 exclude(:test_unterminated_heredoc, "unknown")