[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 9dbab36313ef9583d14b0a72c32ab1bc17fe41ab..ba1a4243d63279bd95091dc9681f584975791267 100644
--- a/Source/core/fetch/Resource.cpp
+++ b/Source/core/fetch/Resource.cpp
@@ -970,6 +970,8 @@ 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);
@@ -1005,6 +1007,8 @@ const char* ResourceTypeName(Resource::Type type)
         return "ImportResource";
     case Resource::Media:
         return "Media";
+    case Resource::Manifest:
+        return "Manifest";
     }
     ASSERT_NOT_REACHED();
     return "Unknown";