Polymer tests require more heap.

sdk/bin/dartanalyzer

 #!/bin/bash --posix
 # Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 set -e
 
 # Setting SCRIPT_DIR this way is ugly, but is needed to handle the case where
 # dart-sdk/bin has been symlinked to. On MacOS, readlink doesn't work
 # with this case.
@@ skipping 47 matching lines @@
 if [ -x /usr/libexec/java_home ]; then
   export JAVA_HOME=$(/usr/libexec/java_home -v '1.6+')
 fi
 
 EXTRA_JVMARGS="-Xss2M "
 OS=`uname | tr "[A-Z]" "[a-z]"`
 if [ "$OS" == "darwin" ] ; then
   # Bump up the heap on Mac VMs, some of which default to 128M or less.
   # Users can specify DART_JVMARGS in the environment to override this
   # setting.
-  EXTRA_JVMARGS+=" -Xmx256M -client "
+  EXTRA_JVMARGS+=" -Xmx512M -client "
 else
   # On other architectures
   # -batch invocations will do better with a server vm
   # invocations for analyzing a single file do better with a client vm
   if [ $FOUND_BATCH -eq 0 ] ; then
     EXTRA_JVMARGS+=" -client "
   fi
 fi
 
 exec java $EXTRA_JVMARGS $DART_JVMARGS -ea -jar \
   "$DART_ANALYZER_LIBS/dartanalyzer.jar" "${DART_SDK[@]}" $@