typescript: introduce devtools_skip_typecheck build flag

This is experimental flag introducing esbuild for typescript transpiler.

I needed to modify some test code to pass tests with esbuild.

Bug: chromium:1278663
DISABLE_THIRD_PARTY_CHECK=need to add esbuild DEPS too
Change-Id: I661951fc4fd8f5e6a2a599e531638ab294f887f2
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3330076
Reviewed-by: Tim Van der Lippe <tvanderlippe@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
diff --git a/scripts/devtools_paths.py b/scripts/devtools_paths.py
index 2fa6a90..bfa7d17 100644
--- a/scripts/devtools_paths.py
+++ b/scripts/devtools_paths.py
@@ -75,6 +75,10 @@
     return path.join(devtools_root_path(), 'scripts', 'hosted_mode', 'server.js')
 
 
+def esbuild_path():
+    return path.join(devtools_root_path(), 'third_party', 'esbuild', 'esbuild')
+
+
 def downloaded_chrome_binary_path():
     return path.abspath(path.join(
     *{