fixes #209, remove tree mutation from CodeChecker

tool/analyze.sh

Index: tool/analyze.sh
diff --git a/tool/analyze.sh b/tool/analyze.sh
index 26c5a0d9e7dbefbe6baa93dd2be41e84db8c16d6..7f1b35e24a38ac3b200ff6fb3ed11ffd88a12232 100755
--- a/tool/analyze.sh
+++ b/tool/analyze.sh
@@ -4,6 +4,11 @@ set -e
 # Switch to the root directory of dev_compiler
 cd $( dirname "${BASH_SOURCE[0]}" )/..
 
+function fail {
+  echo -e "Analyzer found problems"
+  return 1
+}
+
 # Run analyzer on bin/devc.dart, as it includes most of the code we care about
 # via transitive dependencies. This seems to be the only fast way to avoid
 # repeated analysis of the same code.