Revert "Fix bold when underscore ahead of asterisk"

This reverts commit cb45b5b.

__tests__/ExpensiMark-HTML-test.js

@@ -26,12 +26,6 @@ test('Test bold within code blocks is skipped', () => {
     expect(parser.replace(testString)).toBe(replacedString);
 });
 
-test('Test _ ahead asterisk still result in bold', () => {
-    const testString = 'bold\n```\n*not a bold*\n```\nThis is _*bold*';
-    const replacedString = 'bold<br /><pre>*not&#32;a&#32;bold*<br /></pre>This is _<strong>bold</strong>';
-    expect(parser.replace(testString)).toBe(replacedString);
-});
-
 test('Test heading markdown replacement', () => {
     let testString = '# Heading should not have new line after it.\n';
     expect(parser.replace(testString)).toBe('<h1>Heading should not have new line after it.</h1>');

lib/ExpensiMark.ts

@@ -461,14 +461,8 @@ export default class ExpensiMark {
                 // \B will match everything that \b doesn't, so it works
                 // for * and ~: https://www.rexegg.com/regex-boundaries.html#notb
                 name: 'bold',
-                regex: /(?<!<[^>]*)(\b_|\B)\*(?![^<]*(?:<\/pre>|<\/code>|<\/a>))((?![\s*])[\s\S]*?[^\s*](?<!\s))\*\B(?![^<]*>)(?![^<]*(<\/pre>|<\/code>|<\/a>))/g,
-                replacement: (_extras, match, g1, g2) => {
-                    if (g1.includes('_')) {
-                        return `${g1}<strong>${g2}</strong>`;
-                    }
-
-                    return g2.includes('</pre>') || this.containsNonPairTag(g2) ? match : `<strong>${g2}</strong>`;
-                },
+                regex: /(?<!<[^>]*)\B\*(?![^<]*(?:<\/pre>|<\/code>|<\/a>))((?![\s*])[\s\S]*?[^\s*](?<!\s))\*\B(?![^<]*>)(?![^<]*(<\/pre>|<\/code>|<\/a>))/g,
+                replacement: (_extras, match, g1) => (g1.includes('</pre>') || this.containsNonPairTag(g1) ? match : `<strong>${g1}</strong>`),
             },
             {
                 name: 'strikethrough',