Give even more memory to internal tests

Some of our targets have insance amounts of library input (~900MB, 150K classes)

Change-Id: If028789ad4ac16ff9d2c5e913583bef8581015c3
diff --git a/tools/internal_test.py b/tools/internal_test.py
index d708095..cb6e882 100755
--- a/tools/internal_test.py
+++ b/tools/internal_test.py
@@ -58,7 +58,7 @@
 TEST_COMMANDS = [
     # Run test.py internal testing.
     ['tools/test.py', '--only_internal', '--slow_tests',
-     '--java_max_memory_size=6G'],
+     '--java_max_memory_size=12G'],
     # Ensure that all internal apps compile.
     ['tools/run_on_app.py', '--ignore-java-version','--run-all', '--out=out']
 ]