refactor: remove unnecessary code in html-parser.js (#8359)

src/compiler/parser/html-parser.js

@@ -26,11 +26,6 @@ const doctype = /^<!DOCTYPE [^>]+>/i
 const comment = /^<!\--/
 const conditionalComment = /^<!\[/
 
-let IS_REGEX_CAPTURING_BROKEN = false
-'x'.replace(/x(.)?/g, function (m, g) {
-  IS_REGEX_CAPTURING_BROKEN = g === ''
-})
-
 // Special Elements (can contain anything)
 export const isPlainTextElement = makeMap('script,style,textarea', true)
 const reCache = {}
@@ -228,12 +223,6 @@ export function parseHTML (html, options) {
     const attrs = new Array(l)
     for (let i = 0; i < l; i++) {
       const args = match.attrs[i]
-      // hackish work around FF bug https://bugzilla.mozilla.org/show_bug.cgi?id=369778
-      if (IS_REGEX_CAPTURING_BROKEN && args[0].indexOf('""') === -1) {
-        if (args[3] === '') { delete args[3] }
-        if (args[4] === '') { delete args[4] }
-        if (args[5] === '') { delete args[5] }
-      }
       const value = args[3] || args[4] || args[5] || ''
       const shouldDecodeNewlines = tagName === 'a' && args[1] === 'href'
         ? options.shouldDecodeNewlinesForHref