tools: increase timeout of running WPT

We run all WPT from one subset in the same process using workers.
As the number of the tests grow, it can take longer to run some of the
subsets, but it's still overall faster than running them in different
processes. This patch increases the timeout
for WPT to prevent the test from failing because it takes longer
to run (even though it would still complete at some point).

tools/test.py

@@ -957,8 +957,14 @@ def GetVm(self, arch, mode):
 
   def GetTimeout(self, mode, section=''):
     timeout = self.timeout * TIMEOUT_SCALEFACTOR[ARCH_GUESS or 'ia32'][mode]
-    if section == 'pummel' or section == 'benchmark' or section == 'wpt':
+    if section == 'pummel' or section == 'benchmark':
       timeout = timeout * 6
+    # We run all WPT from one subset in the same process using workers.
+    # As the number of the tests grow, it can take longer to run some of the
+    # subsets, but it's still overall faster than running them in different
+    # processes.
+    elif section == 'wpt':
+      timeout = timeout * 12
     return timeout
 
 def RunTestCases(cases_to_run, progress, tasks, flaky_tests_mode, measure_flakiness):