Split the dart_sdk bot script into two runs, one with only apidocs.

tools/bots/dart_sdk.py

Index: tools/bots/dart_sdk.py
diff --git a/tools/bots/dart_sdk.py b/tools/bots/dart_sdk.py
index 3b70f46de25222333ba7b3851489139695e7d834..f449293726b955c8f4f0b45f17bbc9abeebbfbb1 100644
--- a/tools/bots/dart_sdk.py
+++ b/tools/bots/dart_sdk.py
@@ -224,11 +224,14 @@ def Run(command, env=None):
   return bot.RunProcess(command, env=env)
 
 if __name__ == '__main__':
-  # We always clobber the bot, to make sure releases are build from scratch
-  force = CHANNEL != bot_utils.Channel.BLEEDING_EDGE
-  bot.Clobber(force=force)
-
-  CreateUploadSDK()
-  if BUILD_OS == 'linux':
-    CreateUploadVersionFile()
-    CreateUploadAPIDocs()
+  if len(sys.argv) > 1 and sys.argv[2] == 'api_docs':
+    if BUILD_OS == 'linux':
+      CreateUploadAPIDocs()
+  else:
+    # We always clobber the bot, to make sure releases are build from scratch
+    force = CHANNEL != bot_utils.Channel.BLEEDING_EDGE
+    bot.Clobber(force=force)
+
+    CreateUploadSDK()
+    if BUILD_OS == 'linux':
+      CreateUploadVersionFile()