fix extract.rb and check_extract.rb

scripts/check_extract.rb

@@ -12,5 +12,5 @@ METHODS.each do |method|
       b = a.to_s.end_with?(".wasm.txt") ? a.sub(".wasm.txt", "-#{pass}.wasm.txt") : a.sub(".txt", "-#{pass}.txt")
       puts "#{a.basename} - #{b.basename}: #{method[:name]}, #{pass}, #{FileUtils.cmp(a, b) ? "○" : "☓"}"
     end
-  end
+  end if method[:name] != "null"
 end

scripts/extract.rb

@@ -11,5 +11,5 @@ METHODS.each do |method|
     extract(out, method[:name])
 
     OPT_PASSES.each {|pass| extract(out.sub(".wasm", "-#{pass}.wasm"), method[:name])}
-  end
+  end if method[:name] != "null"
 end