Update double-conversion to 7630f84a10f9428b041d0471e71a562141e9684b.

Change-Id: I37d176a938798cb74eae0a3a445182beb55a117d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/434900
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>

PRESUBMIT.py

@@ -340,7 +340,8 @@ def _CheckClangFormat(input_api, output_api):
                     f.ChangedContents())):
             is_deps = True
             break
-        if is_cpp_file(path) and os.path.isfile(path):
+        if is_cpp_file(path) and os.path.isfile(
+                path) and not path.startswith('third_party/'):
             files.append(path)
 
     if is_deps: