MIPS: skip webkit/dfg-int-overflow-in-loop on big-endian.

The boards on the bots do not have FPU, and therefore time out on
this test.

BUG=
NOTRY=true

Review URL: https://codereview.chromium.org/1411313003

Cr-Commit-Position: refs/heads/master@{#31395}

test/webkit/webkit.status

@@ -62,6 +62,10 @@
   # Doesn't work with gcc 4.6 on arm or arm64 for some reason.
   'reentrant-caching': [SKIP],
 }],  # 'dcheck_always_on == True and (arch == arm or arch == arm64)'
+['arch == mips', {
+  # Too slow for mips big-endian boards on bots (no FPU).
+  'dfg-int-overflow-in-loop': [SKIP],
+}], # 'arch == mips'
 
 ##############################################################################
 ['asan == True', {