Add --optimize_for_size to tests flag matrix.

tools/run-tests.py

Index: tools/run-tests.py
diff --git a/tools/run-tests.py b/tools/run-tests.py
index dfe90368aed7c41a89286ce6515be51e8c56616e..f15fd4582a5725372a61d4ea77a47147bee7731a 100755
--- a/tools/run-tests.py
+++ b/tools/run-tests.py
@@ -54,6 +54,7 @@ TIMEOUT_SCALEFACTOR = {"debug"   : 4,
 
 # Use this to run several variants of the tests.
 VARIANT_FLAGS = [[],
+                 ["--optimize-for-size"],

[Sven Panne, 2013/10/29 12:43:31]

I am not sure if this is the right way to proceed, because it will blow up our
test times significantly. Of course it would be a nice-to-have for each flag,
but we can't afford this due to combinatorial explosion.

Perhaps we can have a runner on our waterfall with this flag enabled instead?

[rmcilroy, 2013/10/29 14:02:55]

I realize this will increase test time by about 25% - that's why I didn't
introduce it in the original CL - but I think it's important to test with this
flag enabled since it significantly changes generated prologue code (and will
change other generated code as more optimizations are added), and the
run-tests.py tests found some issues which weren't apparent when running the JS
benchmarks.

Having a runner (for each arch) with this flag enabled would be OK, but are
there extra runners available on which we can enable this flag (from what I can
see, there is only a single ARM runner on the V8 waterfall, and I think we want
to test both with and without the flag).  Thoughts?

                  ["--stress-opt", "--always-opt"],
                  ["--nocrankshaft"]]
 MODE_FLAGS = {