[file_packager] Add missing support_node check when using preload cache (#23059)

Fixes an error "isNode is not defined" error when using the preload cache
and building with -sENVIRONMENT=web.

Author: dashodanger

test/test_browser.py

@@ -633,10 +633,17 @@ def test_preload_caching(self, extra_size):
       self.skipTest('chrome bug')
     create_file('somefile.txt', '''load me right before running the code please''' + ('_' * extra_size))
     print('size:', os.path.getsize('somefile.txt'))
-    self.compile_btest('main.c', ['--use-preload-cache', '--js-library', 'test.js', '--preload-file', 'somefile.txt', '-o', 'page.html', '-sALLOW_MEMORY_GROWTH'], reporting=Reporting.JS_ONLY)
+    args = ['--use-preload-cache', '--js-library', 'test.js', '--preload-file', 'somefile.txt', '-o', 'page.html', '-sALLOW_MEMORY_GROWTH']
+    self.compile_btest('main.c', args, reporting=Reporting.JS_ONLY)
     self.run_browser('page.html', '/report_result?exit:0')
     self.run_browser('page.html', '/report_result?exit:1')
 
+    # test with ENVIRONMENT=web, to check for problems with node.js support
+    # (see #23059)
+    self.clear_indexed_db()
+    self.compile_btest('main.c', args + ['-sENVIRONMENT=web'], reporting=Reporting.JS_ONLY)
+    self.run_browser('page.html', '/report_result?exit:0')
+
   def test_preload_caching_indexeddb_name(self):
     self.set_setting('EXIT_RUNTIME')
     create_file('somefile.txt', '''load me right before running the code please''')

tools/file_packager.py

@@ -792,10 +792,13 @@ def generate_js(data_target, data_files, metadata):
         var DB_VERSION = 1;
         var METADATA_STORE_NAME = 'METADATA';
         var PACKAGE_STORE_NAME = 'PACKAGES';
-        function openDatabase(callback, errback) {
-          if (isNode) {
-            return errback();
-          }
+        function openDatabase(callback, errback) {'''
+      if options.support_node:
+        code += '''
+            if (isNode) {
+              return errback();
+            }'''
+      code += '''
           var indexedDB;
           if (typeof window === 'object') {
             indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;