fix(compiler): avoid converting &nbps; to spaces (fix vuejs#11059)

The regex for whitespace was too strict and was causing $nbps; chars to
disappear from templates when `whitespace: 'condense'` is set. Changing the rule
to avoid converting non-breaking white space chars into regular spaces.

Author: despreston

src/compiler/parser/index.js

@@ -38,7 +38,7 @@ const modifierRE = /\.[^.\]]+(?=[^\]]*$)/g
 const slotRE = /^v-slot(:|$)|^#/
 
 const lineBreakRE = /[\r\n]/
-const whitespaceRE = /\s+/g
+const whitespaceRE = /[ \t\r\n]+/g
 
 const invalidAttributeRE = /[\s"'<>\/=]/
 

test/unit/modules/compiler/parser.spec.js

@@ -845,6 +845,14 @@ describe('parser', () => {
     expect(ast.children[4].children[0].text).toBe('. Have fun! ')
   })
 
+  it(`maintains   with whitespace: 'condense'`, () => {
+    const options = extend({}, condenseOptions)
+    const ast = parse('<span>&nbsp;</span>', options)
+    const code = ast.children[0]
+    expect(code.type).toBe(3)
+    expect(code.text).toBe('\xA0')
+  })
+
   it(`preserve whitespace in <pre> tag with whitespace: 'condense'`, function () {
     const options = extend({}, condenseOptions)
     const ast = parse('<pre><code>  \n<span>hi</span>\n  </code><span> </span></pre>', options)