Only do this optimization for method scopes

Non-method scopes like classes and modules have issues with the
frame name not properly propagating into the executing body, and
blocks may be used for define_method which introduces similar
complexities in getting the frame name. This patch temporarily
narrows the frame name optimization to method bodies only.

core/src/main/java/org/jruby/ir/builder/IRBuilderAST.java

@@ -2655,8 +2655,11 @@ public Operand buildVCall(Variable result, VCallNode node) {
         switch (callName) {
             case "__method__":
             case "__callee__":
-                addInstr(new FrameNameCallInstr(result, callName));
-                return result;
+                // narrow to methods until we can fix other scopes' frame names
+                if (scope instanceof IRMethod) {
+                    addInstr(new FrameNameCallInstr(result, callName));
+                    return result;
+                }
         }
 
         return _call(result, VARIABLE, buildSelf(), node.getName());