Android: Make errorprone faster

Curtesy of cushon@:
There are javac flags that tell it to stop at a particular compilation
phase: -XDshould-stop.ifNoError=FLOW should allow Error Prone to run but
stop the compilation before code is generated.

4 seconds faster for chrome_java errorprone. (55s -> 51s).
5.2s faster for Base Java Signature Change (153.6s -> 148.4s).
Saves 192.9s elapsed time for Base Java Signature Change.
    4552.2s -> 4359.3s

Bug: 906803
Change-Id: I0708cafea2f95ba50df7697d753ea3e930d1330c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2134192Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#755906}

build/android/gyp/compile_java.py

@@ -624,6 +624,10 @@ def main(argv):
     if not options.warnings_as_errors:
       errorprone_flags.append('-XepAllErrorsAsWarnings')
     javac_args += ['-XDcompilePolicy=simple', ' '.join(errorprone_flags)]
+    # This flag quits errorprone after checks and before code generation, since
+    # we do not need errorprone outputs, this speeds up errorprone by 4 seconds
+    # for chrome_java.
+    javac_args += ['-XDshould-stop.ifNoError=FLOW']
 
   if options.java_version:
     javac_args.extend([