Make pub strong-mode clean.

lib/src/command/cache_repair.dart

Index: lib/src/command/cache_repair.dart
diff --git a/lib/src/command/cache_repair.dart b/lib/src/command/cache_repair.dart
index 6c238fa149dfa4fd5ce7b6d92e6c7b8339d79d0d..902f4458e4872b5fea650a17dfb0c05c15461676 100644
--- a/lib/src/command/cache_repair.dart
+++ b/lib/src/command/cache_repair.dart
@@ -25,11 +25,11 @@ class CacheRepairCommand extends PubCommand {
 
     // Repair every cached source.
     for (var source in cache.sources.all.map(cache.source)) {
-      if (source is! CachedSource) continue;
-
-      var results = await source.repairCachedPackages();
-      successes.addAll(results.first);
-      failures.addAll(results.last);
+      if (source is CachedSource) {
+        var results = await source.repairCachedPackages();
+        successes.addAll(results.first);
+        failures.addAll(results.last);
+      }
     }
 
     if (successes.length > 0) {