Remove AOT (#5340)

* make `jit` mode the default when no mode is specified

* unify JIT and AOT codepaths

* ensure `Object.entries` on undefined doesn't break

It could be that sometimes you don't have values in your config (e.g.: `presets: []`), this in turn will break some plugins where we assume we have a value.

* drop AOT specific tests

These tests are all covered by JIT mode already and were AOT specific.

* simplify tests, and add a few

Some of the tests were written for AOT specifically, some were missing. We also updated the way we write those tests, essentially making Tailwind a blackbox, by testing against the final output.
Now that JIT mode is the default, this is super fast because we only generate what is used, instead of partially testing in a 3MB file or building it all, then purging.

* add some todo's to make sure we warn in a few cases

* make `darkMode: 'media'`, the default

This also includes moving dark mode tests to its own dedicated file.

* remove PostCSS 7 compat mode

* update CLI to be JIT-first

* fix integration tests

This is not a _real_ fix, but it does solve the broken test for now.

* warn when using @responsive or @variants

* remove the JIT preview warning

* remove AOT-only code paths

* remove all `mode: 'jit'` blocks

Also remove `variants: {}` since they are not useful in `JIT` mode
anymore.

* drop unused dependencies

* rename `purge` to `content`

* remove static CDN builds

* mark `--purge` as deprecated in the CLI

This will still work, but a warning will be printed and it won't show up
in the `--help` output.

* cleanup nesting plugin

We don't have to duplicate it anymore since there is no PostCSS 7
version anymore.

* make sure integration tests run in band

* cleanup folder structure

* make sure nesting folder is available

* simplify resolving of purge/content information

integrations/tailwindcss-cli/tests/cli.test.js

@@ -115,9 +115,7 @@ describe('Build command', () => {
 
     let customConfig = `module.exports = ${JSON.stringify(
       {
-        purge: ['./src/index.html'],
-        mode: 'jit',
-        darkMode: false, // or 'media' or 'class'
+        content: ['./src/index.html'],
         theme: {
           extend: {
             fontWeight: {
@@ -125,9 +123,6 @@ describe('Build command', () => {
             },
           },
         },
-        variants: {
-          extend: {},
-        },
         corePlugins: {
           preflight: false,
         },
@@ -258,7 +253,7 @@ describe('Build command', () => {
 
     expect(combined).toMatchInlineSnapshot(`
       "
-      tailwindcss v2.2.8
+      tailwindcss v2.2.9
 
       Usage:
          tailwindcss build [options]
@@ -267,8 +262,7 @@ describe('Build command', () => {
          -i, --input              Input file
          -o, --output             Output file
          -w, --watch              Watch for changes and rebuild as needed
-             --jit                Build using JIT mode
-             --purge              Content paths to use for removing unused classes
+             --content            Content paths to use for removing unused classes
              --postcss            Load custom PostCSS configuration
          -m, --minify             Minify the output
          -c, --config             Path to a custom config file
@@ -298,34 +292,6 @@ describe('Init command', () => {
     expect((await readOutputFile('../full.config.js')).split('\n').length).toBeGreaterThan(50)
   })
 
-  test('--jit', async () => {
-    cleanupFile('with-jit.config.js')
-
-    let { combined } = await $(`${EXECUTABLE} init with-jit.config.js --jit`)
-
-    expect(combined).toMatchInlineSnapshot(`
-      "
-      Created Tailwind CSS config file: with-jit.config.js
-      "
-    `)
-
-    expect(await readOutputFile('../with-jit.config.js')).toContain("mode: 'jit'")
-  })
-
-  test('--full, --jit', async () => {
-    cleanupFile('full-with-jit.config.js')
-
-    let { combined } = await $(`${EXECUTABLE} init full-with-jit.config.js --jit --full`)
-
-    expect(combined).toMatchInlineSnapshot(`
-      "
-      Created Tailwind CSS config file: full-with-jit.config.js
-      "
-    `)
-
-    expect(await readOutputFile('../full-with-jit.config.js')).toContain("mode: 'jit'")
-  })
-
   test('--postcss', async () => {
     expect(await fileExists('postcss.config.js')).toBe(true)
     await removeFile('postcss.config.js')
@@ -348,13 +314,12 @@ describe('Init command', () => {
 
     expect(combined).toMatchInlineSnapshot(`
       "
-      tailwindcss v2.2.8
+      tailwindcss v2.2.9
 
       Usage:
          tailwindcss init [options]
 
       Options:
-             --jit                Initialize for JIT mode
          -f, --full               Initialize a full \`tailwind.config.js\` file
          -p, --postcss            Initialize a \`postcss.config.js\` file
          -h, --help               Display usage information