[ruby/prism] Extract snippet into its own file and skip in TruffleRuby

https://github.com/ruby/prism/commit/12649ee74c

test/prism/fixtures/emoji_method_calls.txt

@@ -0,0 +1 @@
+foo.🌊 = 1

test/prism/fixtures/method_calls.txt

@@ -20,8 +20,6 @@ a::b c
 
 foo.bar = 1
 
-foo.🌊 = 1
-
 a?
 
 a(&block)

test/prism/parse_test.rb

@@ -87,7 +87,7 @@ module Prism
 
     relatives.each do |relative|
       # These fail on TruffleRuby due to a difference in Symbol#inspect: :测试 vs :"测试"
-      next if RUBY_ENGINE == "truffleruby" and %w[seattlerb/bug202.txt seattlerb/magic_encoding_comment.txt].include?(relative)
+      next if RUBY_ENGINE == "truffleruby" and %w[emoji_method_calls.txt seattlerb/bug202.txt seattlerb/magic_encoding_comment.txt].include?(relative)
 
       filepath = File.join(base, relative)
       snapshot = File.expand_path(File.join("snapshots", relative), __dir__)