Configure recipe-based Linux chromium.webkit builders

BUG=460949
R=primiano@chromium.org

Review URL: https://codereview.chromium.org/964873005

Cr-Commit-Position: refs/heads/master@{#319065}

testing/buildbot/chromium.webkit.json

@@ -17,6 +17,42 @@
       }
     ]
   },
+  "WebKit Linux 32": {
+    "gtest_tests": [
+      "blink_heap_unittests",
+      "blink_platform_unittests",
+      "webkit_unit_tests",
+      "wtf_unittests"
+    ],
+    "scripts": [
+      {
+        "name": "webkit_lint",
+        "script": "webkit_lint.py"
+      },
+      {
+        "name": "webkit_python_tests",
+        "script": "webkit_python_tests.py"
+      }
+    ]
+  },
+  "WebKit Linux (dbg)": {
+    "gtest_tests": [
+      "blink_heap_unittests",
+      "blink_platform_unittests",
+      "webkit_unit_tests",
+      "wtf_unittests"
+    ],
+    "scripts": [
+      {
+        "name": "webkit_lint",
+        "script": "webkit_lint.py"
+      },
+      {
+        "name": "webkit_python_tests",
+        "script": "webkit_python_tests.py"
+      }
+    ]
+  },
   "Linux ChromiumOS Tests (1)": {
     "gtest_tests": [
       "accessibility_unittests",