Ensure we minify whitespace, even when transpiling using babel (#21882)

We could instead rely try to configure babel do this, but it seems more
consistent to simply run our existing minifier again.

Fixes: #21881

Author: sbc100

test/test_other.py

@@ -13365,7 +13365,7 @@ def test_hello_function(self):
 
   @parameterized({
     '': ([],),
-    'O2': (['-O2'],),
+    'O3': (['-O3'],),
   })
   @crossplatform
   def test_es5_transpile(self, args):
@@ -13478,6 +13478,9 @@ def check_for_es6(filename, expect):
     self.set_setting('LEGACY_VM_SUPPORT')
     self.do_runf('test.c', expected, output_basename='test_old')
     check_for_es6('test_old.js', False)
+    if '-O3' in args:
+      # Verify that output is minified
+      self.assertEqual(len(read_file('test_old.js').splitlines()), 1)
 
     # If we add `-sPOLYFILL=0` that transpiler is not run at all
     print('with old browser + -sPOLYFILL=0')

tools/link.py

@@ -2228,11 +2228,15 @@ def phase_binaryen(target, options, wasm_target):
     if options.use_closure_compiler:
       with ToolchainProfiler.profile_block('closure_compile'):
         final_js = building.closure_compiler(final_js, extra_closure_args=options.closure_args)
-      save_intermediate_with_wasm('closure', wasm_target)
+      save_intermediate('closure')
+
     if settings.TRANSPILE:
       with ToolchainProfiler.profile_block('transpile'):
         final_js = building.transpile(final_js)
-      save_intermediate_with_wasm('traspile', wasm_target)
+      save_intermediate('transpile')
+      # Run acorn one more time to minify whitespace after babel runs
+      if settings.MINIFY_WHITESPACE:
+        final_js = building.acorn_optimizer(final_js, ['--minify-whitespace'])
 
   if settings.ASYNCIFY_LAZY_LOAD_CODE:
     with ToolchainProfiler.profile_block('asyncify_lazy_load_code'):