Move internal modules to “internal” folder.

.internal/unescapeHtmlChar.js

@@ -0,0 +1,21 @@
+import basePropertyOf from './.internal/basePropertyOf.js';
+
+/** Used to map HTML entities to characters. */
+const htmlUnescapes = {
+  '&': '&',
+  '&lt;': '<',
+  '&gt;': '>',
+  '&quot;': '"',
+  '&#39;': "'"
+};
+
+/**
+ * Used by `unescape` to convert HTML entities to characters.
+ *
+ * @private
+ * @param {string} chr The matched character to unescape.
+ * @returns {string} Returns the unescaped character.
+ */
+const unescapeHtmlChar = basePropertyOf(htmlUnescapes);
+
+export default unescapeHtmlChar;