[DevTools]: Moves common to ES modules

This CL converts the contents of the common/ folder over to ES modules
from the current custom module system. It includes statements in each
file that will pollute the global namespace, allowing the non-ESM code
to continue working as before.

Bug: 1006759
Change-Id: Ib591e49155000381f85999a5da6c467ad0160996
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1816563
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Paul Lewis <aerotwist@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#699728}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: e064553334d4b0c925f0b1f0e2e0234be66b71be
diff --git a/scripts/compile_frontend.py b/scripts/compile_frontend.py
index 78a553d..afe10c5 100755
--- a/scripts/compile_frontend.py
+++ b/scripts/compile_frontend.py
@@ -279,9 +279,9 @@
         '--externs',
         namespace_externs_path,
         '--js',
-        RUNTIME_FILE,
-        '--js',
         ROOT_MODULE_FILE,
+        '--js',
+        RUNTIME_FILE,
     ]
 
     all_files = descriptors.all_compiled_files()
@@ -318,7 +318,6 @@
     namespace_externs_file = tempfile.NamedTemporaryFile(mode='wt', delete=False)
     try:
         for namespace in namespaces:
-            namespace_externs_file.write('/** @const */\n')
             namespace_externs_file.write('var %s = {};\n' % namespace)
     finally:
         namespace_externs_file.close()