avm2: Partially implement `toLocaleString` insamuch as is necessary to run Array tests on it.

This appears to work almost like it's own TObject method; you can run `Object.prototype.toLocaleString` on all sorts of things and it has separate behavior to what the class method for it might be. I have attempted to match Flash Player as best as I can.

core/src/avm2/globals/object.rs

@@ -46,7 +46,7 @@ fn to_locale_string<'gc>(
     _: &[Value<'gc>],
 ) -> Result<Value<'gc>, Error> {
     Ok(this
-        .map(|t| t.to_string(activation.context.gc_context))
+        .map(|t| t.to_locale_string(activation.context.gc_context))
         .unwrap_or(Ok(Value::Undefined))?)
 }
 

core/src/avm2/object.rs

@@ -673,6 +673,23 @@ pub trait TObject<'gc>: 'gc + Collect + Debug + Into<Object<'gc>> + Clone + Copy
     /// coercions.
     fn to_string(&self, mc: MutationContext<'gc, '_>) -> Result<Value<'gc>, Error>;
 
+    /// Implement the result of calling `Object.prototype.toLocaleString` on this
+    /// object class.
+    ///
+    /// `toLocaleString` is a method used to request an object be coerced to a
+    /// locale-dependent string value. The default implementation appears to
+    /// generate a debug-style string based on the name of the class this
+    /// object is, in the format of `[object Class]` (where `Class` is the name
+    /// of the class that created this object).
+    fn to_locale_string(&self, mc: MutationContext<'gc, '_>) -> Result<Value<'gc>, Error> {
+        let class_name = self
+            .as_proto_class()
+            .map(|c| c.read().name().local_name())
+            .unwrap_or_else(|| "Object".into());
+
+        Ok(AvmString::new(mc, format!("[object {}]", class_name)).into())
+    }
+
     /// Implement the result of calling `Object.prototype.valueOf` on this
     /// object class.
     ///

core/src/avm2/object/function_object.rs

@@ -288,6 +288,10 @@ impl<'gc> TObject<'gc> for FunctionObject<'gc> {
         }
     }
 
+    fn to_locale_string(&self, mc: MutationContext<'gc, '_>) -> Result<Value<'gc>, Error> {
+        self.to_string(mc)
+    }
+
     fn value_of(&self, _mc: MutationContext<'gc, '_>) -> Result<Value<'gc>, Error> {
         Ok(Value::Object(Object::from(*self)))
     }

core/src/avm2/object/primitive_object.rs

@@ -79,6 +79,20 @@ impl<'gc> TObject<'gc> for PrimitiveObject<'gc> {
         Ok(self.0.read().primitive.clone())
     }
 
+    fn to_locale_string(&self, mc: MutationContext<'gc, '_>) -> Result<Value<'gc>, Error> {
+        match self.0.read().primitive.clone() {
+            val @ Value::Integer(_) | val @ Value::Unsigned(_) => Ok(val),
+            _ => {
+                let class_name = self
+                    .as_proto_class()
+                    .map(|c| c.read().name().local_name())
+                    .unwrap_or_else(|| "Object".into());
+
+                Ok(AvmString::new(mc, format!("[object {}]", class_name)).into())
+            }
+        }
+    }
+
     fn value_of(&self, _mc: MutationContext<'gc, '_>) -> Result<Value<'gc>, Error> {
         Ok(self.0.read().primitive.clone())
     }