Add presubmit trybuilder to Luci-GAE repository.

masters/master.tryserver.infra/builders.pyl

 {
   "master_base_class": "Master4a",
   "master_classname": "InfraTryServer",
   "master_port": 21402,
   "master_port_alt": 41402,
   "slave_port": 31402,
   "templates": [
     "../master.chromium.infra/templates",
     "../master.chromium/templates",
   ],
@@ skipping 45 matching lines @@
       "category": "Luci-py",
       "recipe": "run_presubmit",
       "properties": {
         "repo_name": "luci_py",
         "runhooks": True,
       },
       "scheduler": None,
       "slave_pools": ["trusty64_slave_pool"],
       "slavebuilddir": "presubmit_lucipy",
     },
+    "Luci-GAE Presubmit": {
+      "category": "Luci-GAE",
+      "recipe": "infra/luci_gae",
+      "scheduler": None,
+      "slave_pools": ["trusty64_slave_pool"],
+      "slavebuilddir": "presubmit_lucigae",
+    },
     "Luci-GAE Linux Trusty 64 Tester": {
       "category": "Luci-GAE",
       "recipe": "infra/luci_gae",
       "scheduler": None,
       "slave_pools": ["trusty64_slave_pool"],
       "slavebuilddir": "luci-gae",
     },
     "Luci-go Presubmit": {
       "category": "Luci-go",
       "recipe": "infra/luci_go",
@@ skipping 61 matching lines @@
     "win64_slave_pool": {
       "slave_data": {
         "bits": 64,
         "os": "win",
         "version": "win7",
       },
       "slaves": ["vm253-m4"],
     },
   },
 }