Enable resolving source field in dev dependencies

Author: devongovett

packages/core/package-manager/src/NodePackageManager.js

@@ -38,17 +38,8 @@ const MAIN = 1 << 0;
 const SOURCE = 1 << 2;
 const NODE_CONDITION = 1 << 3;
 const SOURCE_CONDITION = 1 << 17;
-const ENTRIES =
-  MAIN |
-  (process.env.PARCEL_BUILD_ENV !== 'production' ||
-  process.env.PARCEL_SELF_BUILD
-    ? SOURCE
-    : 0);
-
-const CONDITIONS =
-  process.env.PARCEL_BUILD_ENV !== 'production' || process.env.PARCEL_SELF_BUILD
-    ? NODE_CONDITION | SOURCE_CONDITION
-    : NODE_CONDITION;
+const ENTRIES = MAIN | SOURCE;
+const CONDITIONS = NODE_CONDITION | SOURCE_CONDITION;
 
 const NODE_MODULES = `${path.sep}node_modules${path.sep}`;