Modularize master branch.

_baseGetTag.js

@@ -0,0 +1,28 @@
+import Symbol from './_Symbol.js';
+import getRawTag from './_getRawTag.js';
+import objectToString from './_objectToString.js';
+
+/** `Object#toString` result references. */
+var nullTag = '[object Null]',
+    undefinedTag = '[object Undefined]';
+
+/** Built-in value references. */
+var symToStringTag = Symbol ? Symbol.toStringTag : undefined;
+
+/**
+ * The base implementation of `getTag` without fallbacks for buggy environments.
+ *
+ * @private
+ * @param {*} value The value to query.
+ * @returns {string} Returns the `toStringTag`.
+ */
+function baseGetTag(value) {
+  if (value == null) {
+    return value === undefined ? undefinedTag : nullTag;
+  }
+  return (symToStringTag && symToStringTag in Object(value))
+    ? getRawTag(value)
+    : objectToString(value);
+}
+
+export default baseGetTag;