Simplify InternalMethod#getArityNumber()

Author: eregon

src/main/java/org/truffleruby/language/methods/Arity.java

@@ -130,6 +130,10 @@ public int getArityNumber(ProcType type) {
         return type == ProcType.PROC ? procArityNumber : arityNumber;
     }
 
+    public int getMethodArityNumber() {
+        return arityNumber;
+    }
+
     public String[] getKeywordArguments() {
         return keywordArguments;
     }

src/main/java/org/truffleruby/language/methods/InternalMethod.java

@@ -14,7 +14,6 @@
 import org.truffleruby.RubyContext;
 import org.truffleruby.core.klass.RubyClass;
 import org.truffleruby.core.module.RubyModule;
-import org.truffleruby.core.proc.ProcType;
 import org.truffleruby.core.proc.RubyProc;
 import org.truffleruby.language.LexicalScope;
 import org.truffleruby.language.Visibility;
@@ -184,7 +183,7 @@ public boolean isBuiltIn() {
     }
 
     public int getArityNumber() {
-        return sharedMethodInfo.getArity().getArityNumber(ProcType.LAMBDA);
+        return sharedMethodInfo.getArity().getMethodArityNumber();
     }
 
     public RootCallTarget getCallTarget() {