Start making server strong mode clean

pkg/analysis_server/lib/src/context_manager.dart

Index: pkg/analysis_server/lib/src/context_manager.dart
diff --git a/pkg/analysis_server/lib/src/context_manager.dart b/pkg/analysis_server/lib/src/context_manager.dart
index fc2573c3f27d0948e2a058e526c54035a4b8b142..ceac78bd14c5dadb00bb058459b073309a60f51b 100644
--- a/pkg/analysis_server/lib/src/context_manager.dart
+++ b/pkg/analysis_server/lib/src/context_manager.dart
@@ -624,15 +624,12 @@ class ContextManagerImpl implements ContextManager {
     }
 
     var analyzer = options[AnalyzerOptions.analyzer];
-    if (analyzer is! Map) {
-      // Done.
-      return;
-    }
-
-    // Set ignore patterns.
-    YamlList exclude = analyzer[AnalyzerOptions.exclude];
-    if (exclude != null) {
-      setIgnorePatternsForContext(info, exclude);
+    if (analyzer is Map) {
+      // Set ignore patterns.
+      YamlList exclude = analyzer[AnalyzerOptions.exclude];
+      if (exclude is List<String>) {
+        setIgnorePatternsForContext(info, exclude as List<String>);

[scheglov, 2016/03/31 00:53:18]

We can propagate the type of "exclude", but it is not enough for strong mode?
That's sad.

[Brian Wilkerson, 2016/03/31 15:27:12]

You're right, that does seem like it ought not to be necessary. I'll back it out
until we get further resolution.

[Leaf, 2016/03/31 17:59:14]

Intellij go to declaration can't seem to find the def of YamlList for me, so I'm
not sure I have the right class, but this YamlList:

https://www.dartdocs.org/documentation/yaml/2.1.8/yaml/YamlList-class.html

is a subtype of List<dynamic>.  That means that YamlList and List<String> are
not subtype related in strong mode (neither is a subtype of the other).  If I
recall correctly how the analyzer's promotion code works, this means no
promotion will happen.  Does that seem right?  Also, I believe that means the
cast will fail in strong mode.

[Brian Wilkerson, 2016/03/31 18:17:06]

Then the right solution is probably to change setIgnorePatternsForContext to
take a List<dynamic> and test the element types in that method.

+      }
     }
   }