Move internal modules to “internal” folder.

.internal/getRawTag.js

@@ -0,0 +1,45 @@
+/** Used for built-in method references. */
+const objectProto = Object.prototype;
+
+/** Used to check objects for own properties. */
+const hasOwnProperty = objectProto.hasOwnProperty;
+
+/**
+ * Used to resolve the
+ * [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring)
+ * of values.
+ */
+const nativeObjectToString = objectProto.toString;
+
+/** Built-in value references. */
+const symToStringTag = Symbol ? Symbol.toStringTag : undefined;
+
+/**
+ * A specialized version of `baseGetTag` which ignores `Symbol.toStringTag` values.
+ *
+ * @private
+ * @param {*} value The value to query.
+ * @returns {string} Returns the raw `toStringTag`.
+ */
+function getRawTag(value) {
+  const isOwn = hasOwnProperty.call(value, symToStringTag);
+  const tag = value[symToStringTag];
+  let unmasked = false;
+
+  try {
+    value[symToStringTag] = undefined;
+    unmasked = true;
+  } catch (e) {}
+
+  const result = nativeObjectToString.call(value);
+  if (unmasked) {
+    if (isOwn) {
+      value[symToStringTag] = tag;
+    } else {
+      delete value[symToStringTag];
+    }
+  }
+  return result;
+}
+
+export default getRawTag;