Turn StringFromByteArrayPrimitiveNode into a real primitive since it's only used internally by TruffleRuby.

Author: nirvdrum

src/main/java/org/truffleruby/core/string/StringNodes.java

@@ -98,7 +98,6 @@
 import org.truffleruby.builtins.CoreMethodArrayArgumentsNode;
 import org.truffleruby.builtins.CoreMethodNode;
 import org.truffleruby.annotations.CoreModule;
-import org.truffleruby.builtins.NonStandard;
 import org.truffleruby.annotations.Primitive;
 import org.truffleruby.builtins.PrimitiveArrayArgumentsNode;
 import org.truffleruby.builtins.PrimitiveNode;
@@ -4328,9 +4327,8 @@ protected Object stringSubstringGeneric(Object string, int codePointOffset, int
 
     }
 
-    @NonStandard
-    @CoreMethod(names = "from_bytearray", onSingleton = true, required = 4, lowerFixnum = { 2, 3 })
-    public abstract static class StringFromByteArrayPrimitiveNode extends CoreMethodArrayArgumentsNode {
+    @Primitive(name = "string_from_bytearray", lowerFixnum = { 1, 2 })
+    public abstract static class StringFromByteArrayPrimitiveNode extends PrimitiveArrayArgumentsNode {
 
         @Specialization
         protected RubyString stringFromByteArray(

src/main/ruby/truffleruby/core/io.rb

@@ -225,7 +225,7 @@ def shift(count = nil, encoding = Encoding::BINARY)
         total = size
         total = count if count and count < total
 
-        str = String.from_bytearray @storage, @start, total, encoding
+        str = Primitive.string_from_bytearray(@storage, @start, total, encoding)
         @start += total
 
         str