chore(build): Remove build products from the Blockly repository (#6475)

* feat(build): Make build tasks invoke their prerequisites

  - Divide gulp targets into three kinds: main sequence,
    manually invokable, and script-only.  The first two categories
    automatically invoke their prerequisites.
  - Give (most of) the affected gulp targets shorter and more memorable
    names that could become their npm script names in future.

* feat(build): Make package tasks invoke their prerequisites

  Have the package task invoke the cleanBuildDir (as well as
  cleanPackageDir) and build tasks.  Remove the checkBuildDir
  task as it is now redundant since a fresh build is done every
  time.

* feat(build): Make git tasks invoke their prerequisites

* feat(build): Make cleanup, license [sic] tasks invoke their prerequisites

  Turns out they don't have any, so this commit just classifies
  their gulp targets according to the established scheme.

* feat(build): Make appengine tasks invoke their prerequisites

  In this case prepareDeployDir will eventually depend on package
  but does not for now.

* feat(build): Have npm scripts run npm ci first where applicable

  Have any npm script that have external effects (e.g. publishing an
  npm package, pushing a new version to appengine, or updating GitHub
  Pages) start by running npm ci to ensure that all dependencies are
  up-to-date with respect to package-lock.json.

  (This is done by npm and not a gulp script because gulp itself
  might need updating.  So might npm, but that is less likely to
  make any difference to what gets published/pushed.)

* chore(build): have tests use package target

  Have the tests just run the package target (with debug flags)
  since that runs the the build target automatically.

* feat(tests): Write Closure Compiler output directly to dist/

  Since they are already UMD-wrapped, have Closure Compiler write
  output chunks directly to RELEASE_DIR, i.e. dist/.

* chore(tests): Use freshly-build files in compressed mode.

  Use the freshly-built build/*_compresssed.js files when bootstrapping
  in compressed mode, rather than using the checked-in files in the
  repository root.

  This helps ensure that compressed and uncompressed mode will be
  testing (as closely as possible) the same code.

  Obsoletes #6218 (though the issues discussed there have not actually
  yet been addressed in this branch).

* chore(build): Write intermediate langfiles to build/msg

  Write the results of create_messages.py to build/msg instead of
  build/msg/js.

* fix(build): Use build/msg/en.js instead of msg/messages.js in tests

  This has no direct effect but fixes a long-standing misdesign
  where we are testing against the input to, rather than the output
  of, the language file processing pipeline.

* feat(demos): Use freshly-built files

  Use the freshly-built dist/*_compresssed.js and build/msg/* files
  rather than using the checked-in files in the repository root.

  This helps ensure that these demos are using the most recent
  version of Blockly (even in the develop branch).

* fix(build): Update appengine deployment to include built files

  Modify the prepareDemos task as follows:

  - Use the git index instead of HEAD, so that most local changes
    will be applied (without copying whatever .gitignored cruft
    might be in the local directory).
  - Run clean and build and then copy build/msg and
    dist/*_compressed.js* to the deploy directory.

  This fixes the problem created by the previous commit, wherein the
  demos relied on built files that were not being deployed to
  appengine.

* fix(build): Update GitHub Pages deployment to include built files

  Modify the updateGithubPages task to run clean and build and
  then git add build/msg dist/*_compressed.js*, so that they will
  be included in the deployed pages.

  This fixes the problem created by the previous^2 commit,
  wherein the demos relied on built files that were not being
  deployed to GitHub Pages.

* chore(build): Remove build products from repository

  Remove *_compressed.js* and msg/js/* from the blockly repository.
  Also remove the now-obsolete checkinBuilt gulp task.

* chore(build): Apply relevant changes to test_tasks.js

  Apply changes made to run_all_tests.sh and check_metadata.sh to
  the corresponding parts of their JS replacements in
  test_tasks.js.

* chore(build): Make updates suggested in PR #6475

  - Remove `clean:builddir` and `clean:releasedir` - `clean`
    is sufficient.
  - Remove duplicate `require` from `appengine_tasks.js`.

* feat(build): Use shorter npm script names

  Since scripts that run build tasks now automatically run their
  prerequisite tasks, the previous naming scheme of task `build`
  running all the `build:subtask`s no longe really makes very
  much sense.

  Additionally, following a chat discussion, there seems to be a
  rough consensus to use "messages" to refer to the .json input
  files, and "langfiles" to the generated .js output files.

  Consequently, simplify npm script names by renaming as follows:

  - "generate:langfiles" -> "messages"
  - "build:langfiles" -> "langfiles"
  - "build:js" -> "tsc"
  - "build:deps" -> "deps"
  - "build:compiled" -> "minify"
  - "build:compressed": delete this synonym for "build:compiled",

  ("minify" was chosen as agnostic to Closure Compiler vs. WebPack.)

* chores(build): Add deprecation notice for old scripts

  To reduce potential confusion/frustration, restore the previous
  npm scripts but have them display a deprecation notice instead
  (note that npm prints the script contents before running it, so
  echo is not needed).

* docs(build): Add comments distinguishing 'messages' from 'langfiles'

scripts/gulpfiles/git_tasks.js

@@ -12,6 +12,7 @@ var gulp = require('gulp');
 var execSync = require('child_process').execSync;
 
 var buildTasks = require('./build_tasks');
+const packageTasks = require('./package_tasks');
 
 const upstream_url = "https://github.com/google/blockly.git";
 
@@ -94,7 +95,11 @@ function pushRebuildBranch(done) {
   done();
 }
 
-// Update github pages with what is currently in develop.
+/**
+ * Update github pages with what is currently in develop.
+ *
+ * Prerequisites (invoked): clean, build.
+ */
 const updateGithubPages = gulp.series(
   function(done) {
     execSync('git stash save -m "Stash for sync"', { stdio: 'inherit' });
@@ -104,20 +109,27 @@ const updateGithubPages = gulp.series(
     done();
   },
   buildTasks.cleanBuildDir,
+  packageTasks.cleanReleaseDir,
   buildTasks.build,
-  buildTasks.checkinBuilt,
   function(done) {
-    execSync('git commit -am "Rebuild"', { stdio: 'inherit' });
-    execSync('git push ' + upstream_url + ' gh-pages --force', { stdio: 'inherit' });
+    execSync('git add build/msg/* dist/*_compressed.js*', {stdio: 'inherit'});
+    execSync('git commit -am "Rebuild"', {stdio: 'inherit'});
+    execSync('git push ' + upstream_url + ' gh-pages --force',
+        {stdio: 'inherit'});
     done();
   }
 );
 
 module.exports = {
-  syncDevelop: syncDevelop,
-  syncMaster: syncMaster,
-  createRC: createRC,
-  updateGithubPages: updateGithubPages,
-  createRebuildBranch: createRebuildBranch,
-  pushRebuildBranch: pushRebuildBranch
-}
+  // Main sequence targets.  Each should invoke any immediate prerequisite(s).
+  updateGithubPages,
+
+  // Manually-invokable targets that invoke prerequisites.
+  createRC,
+
+  // Legacy script-only targets, to be deleted.
+  syncDevelop,
+  syncMaster,
+  createRebuildBranch,
+  pushRebuildBranch,
+};