cache: actually fix script assembly encoding

cache/src/main/java/net/runelite/cache/io/OutputStream.java

@@ -26,9 +26,10 @@ package net.runelite.cache.io;
 
 import com.google.common.base.Preconditions;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.Buffer;
 import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.charset.Charset;
 
 public final class OutputStream extends java.io.OutputStream
 {
@@ -57,7 +58,7 @@ public final class OutputStream extends java.io.OutputStream
 			int newCapacity = buffer.capacity() * 2;
 
 			ByteBuffer old = buffer;
-			((Buffer) old).flip();
+			old.flip();
 
 			buffer = ByteBuffer.allocate(newCapacity);
 
@@ -182,16 +183,17 @@ public final class OutputStream extends java.io.OutputStream
 
 	public void writeString(String str)
 	{
-		byte[] b;
-		try
-		{
-			b = str.getBytes("ISO-8859-1");
-		}
-		catch (UnsupportedEncodingException ex)
-		{
-			throw new RuntimeException(ex);
-		}
-		writeBytes(b);
+		Charset utf8charset = Charset.forName("UTF-8");
+		Charset cp1252charset = Charset.forName("Cp1252");
+
+		ByteBuffer inputBuffer = ByteBuffer.wrap(str.getBytes());
+
+		CharBuffer data = utf8charset.decode(inputBuffer);
+
+		ByteBuffer outputBuffer = cp1252charset.encode(data);
+		byte[] outputData = outputBuffer.array();
+
+		writeBytes(outputData);
 		writeByte(0);
 	}
 
@@ -209,4 +211,4 @@ public final class OutputStream extends java.io.OutputStream
 		buffer.put((byte) b);
 	}
 
-}
+}