[gardening] Ensure crashpad_handler is in executables list for Windows.

Follow-up to https://dart.googlesource.com/sdk/+/68849148fde1b07aa1ca18af92139a144b773413

Change-Id: I72af6582566a1c96ebc16a088a3512f7b42a5f7b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/402780
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>

tools/task_kill.py

@@ -24,6 +24,7 @@ POSIX_INFO = 'ps -p %s -o args'
 EXECUTABLE_NAMES = {
     'win32': {
         'chrome': 'chrome.exe',
+        'crashpad_handler': 'crashpad_handler.exe',
         'dart': 'dart.exe',
         'dartaotruntime': 'dartaotruntime.exe',
         'firefox': 'firefox.exe',