Revert "XFail mapper due to https://bugs.swift.org/browse/SR-8778"

This reverts commit f6e581b.

Author: shahmishal

projects.json

@@ -2617,23 +2617,7 @@
         "project": "Mapper.xcodeproj",
         "target": "Mapper",
         "destination": "generic/platform=watchOS",
-        "configuration": "Release",
-        "xfail": {
-          "compatibility": {
-            "4.0": {
-              "branch": {
-                "master": "https://bugs.swift.org/browse/SR-8778",
-                "swift-4.2-branch": "https://bugs.swift.org/browse/SR-8778"
-              }
-            },
-            "4.2": {
-              "branch": {
-                "master": "https://bugs.swift.org/browse/SR-8778",
-                "swift-4.2-branch": "https://bugs.swift.org/browse/SR-8778"
-              }
-            }
-          }
-        }
+        "configuration": "Release"
       },
       {
         "action": "BuildSwiftPackage",