Fix extracting utilities from slim/pug templates

A class name starting with number like `2xl:bg-red-500` must not be removed.

Resolves tailwindlabs#14005

Author: ledermann

src/lib/defaultExtractor.js

@@ -32,7 +32,7 @@ export function defaultExtractor(context) {
         // If the next segment is a number, discard both, for example seeing
         // `px-1` and `5` means the real candidate was `px-1.5` which is already
         // captured.
-        let next = parseInt(segments[idx + 1])
+        let next = Number(segments[idx + 1])
         if (isNaN(next)) {
           results.push(segment)
         } else {

tests/default-extractor.test.js

@@ -476,6 +476,16 @@ test('classes in slim templates', async () => {
   expect(extractions).toContain('text-gray-500')
 })
 
+test('classes in slim templates starting with number', async () => {
+  const extractions = defaultExtractor(`
+    .bg-green-300.2xl:bg-red-300
+      '(Look mom, no closing tag!)
+  `)
+
+  expect(extractions).toContain('bg-green-300')
+  expect(extractions).toContain('2xl:bg-red-300')
+})
+
 test("classes with fractional numeric values don't also generate the whole number utility", async () => {
   const extractions = defaultExtractor(`
     <div class="px-1.5 py-2.75">Hello world!</div>