Fix analyzer to not change the working directory.

I didn't understand what was going on before. Now I do. This is a better fix that making the path absolute.

sky/tools/skyanalyzer

@@ -49,10 +49,10 @@ def main():
 
     try:
       subprocess.check_output([
-          DARTANALYZER, "--package-warnings", os.path.abspath(args.app_path),
+          DARTANALYZER, "--package-warnings", args.app_path,
           "--package-root", os.path.join(WORKBENCH, "packages"),
           "--fatal-warnings"
-      ], stderr=subprocess.STDOUT, cwd=WORKBENCH)
+      ], stderr=subprocess.STDOUT)
     except subprocess.CalledProcessError as e:
       errors = [l for l in e.output.split('\n')
                 if not any(p.match(l) for p in _IGNORED_PATTERNS)]

travis/build.sh

@@ -3,4 +3,4 @@ set -ex
 
 ./sky/tools/gn --release
 ninja -j 4 -C out/Release
-./sky/tools/skyanalyzer --congratulate ../../../examples/stocks/lib/main.dart
+./sky/tools/skyanalyzer --congratulate examples/stocks/lib/main.dart