[NotLanded] Implement the fetching algorithm of the Web Manifest.

Source/core/fetch/Resource.cpp

Index: Source/core/fetch/Resource.cpp
diff --git a/Source/core/fetch/Resource.cpp b/Source/core/fetch/Resource.cpp
index b8084e9b52fd71ec90bd55ebea97c266c9f25e27..4edd35a0e9e9b75966d3aba208dc78ba658750c4 100644
--- a/Source/core/fetch/Resource.cpp
+++ b/Source/core/fetch/Resource.cpp
@@ -956,6 +956,8 @@ const char* Resource::resourceTypeToString(Type type, const FetchInitiatorInfo&
         return "Imported resource";
     case Resource::Media:
         return "Media";
+    case Resource::Manifest:
+        return "Manifest";
     }
     ASSERT_NOT_REACHED();
     return initatorTypeNameToString(initiatorInfo.name);
@@ -993,6 +995,8 @@ const char* ResourceTypeName(Resource::Type type)
         return "ImportResource";
     case Resource::Media:
         return "Media";
+    case Resource::Manifest:
+        return "Manifest";
     }
     ASSERT_NOT_REACHED();
     return "Unknown";