bind-gen: Attempt to fix a build failure on a certain Windows env

Minimizes the path length (/a/../b/c => /b/c).

Bug: 839389, 1046970
Change-Id: Ie5a1879fdb1cfcccc3224ecb2cc62c32346c20a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2040798Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738873}

third_party/blink/renderer/bindings/scripts/bind_gen/__init__.py

@@ -12,7 +12,8 @@ def _setup_sys_path():
     expected_path = 'third_party/blink/renderer/bindings/scripts/bind_gen/'
 
     this_dir = os.path.dirname(__file__)
-    root_dir = os.path.join(this_dir, *(['..'] * expected_path.count('/')))
+    root_dir = os.path.abspath(
+        os.path.join(this_dir, *(['..'] * expected_path.count('/'))))
 
     sys.path = [
         # //third_party/blink/renderer/bindings/scripts/web_idl

third_party/blink/renderer/bindings/scripts/web_idl/__init__.py

@@ -12,7 +12,9 @@ def _setup_sys_path():
     expected_path = 'third_party/blink/renderer/bindings/scripts/web_idl/'
 
     this_dir = os.path.dirname(__file__)
-    root_dir = os.path.join(this_dir, *(['..'] * expected_path.count('/')))
+    root_dir = os.path.abspath(
+        os.path.join(this_dir, *(['..'] * expected_path.count('/'))))
+
     sys.path = [
         # //third_party/blink/renderer/build/scripts/blinkbuild
         os.path.join(root_dir, 'third_party', 'blink', 'renderer', 'build',