Revert "Use 0 as class reader flags in Modlauncher bytecode provider (#…

…137)"

This reverts commit e779303.

src/modlauncher/java/org/spongepowered/asm/launch/MixinLaunchPluginLegacy.java

@@ -235,7 +235,7 @@ public ClassNode getClassNode(String name, boolean runTransformers) throws Class
         if (classBytes != null && classBytes.length != 0) {
             ClassNode classNode = new ClassNode();
             ClassReader classReader = new MixinClassReader(classBytes, canonicalName);
-            classReader.accept(classNode, 0);
+            classReader.accept(classNode, ClassReader.EXPAND_FRAMES);
             return classNode;
         }