Added a test for dump-info with lots of closures.

sdk/lib/_internal/compiler/implementation/inferrer/type_graph_inferrer.dart

Index: sdk/lib/_internal/compiler/implementation/inferrer/type_graph_inferrer.dart
diff --git a/sdk/lib/_internal/compiler/implementation/inferrer/type_graph_inferrer.dart b/sdk/lib/_internal/compiler/implementation/inferrer/type_graph_inferrer.dart
index d7375f66a2b2358fd66003d7bf6c797eb2ec6d2e..8991331f088b409f67343351abd6e2fbc7ec34dc 100644
--- a/sdk/lib/_internal/compiler/implementation/inferrer/type_graph_inferrer.dart
+++ b/sdk/lib/_internal/compiler/implementation/inferrer/type_graph_inferrer.dart
@@ -1127,6 +1127,11 @@ class TypeGraphInferrer implements TypesInferrer {
     // The inferrer stores the return type for a function, so we have to
     // be careful to not return it here.
     if (element is FunctionElement) return compiler.typesTask.functionType;
+
+    // If the inferrer is null, that means that this TypeGraphInferrer
+    // was not initialized by analyzing main.  Nothing can be done in this
+    // case, so return null indicating that the type could not be inferred.

[sra1, 2014/08/13 21:45:26]

When does this happen?
When the input is has parse errors?
Perhaps the underlying condition (e.g. parse error) should block whatever task
is calling getTypeOfElement.

[Ty Overby (Google), 2014/08/13 22:00:31]

This happens on otherwise perfectly behaving code when DumpInfoTask tries to
look up the type of some elements.  This condition is not hit in any real-world
code that I've tried, but it did unexpectedly break when analyzing the
many-closures test case that you suggested.

[sra1, 2014/08/13 22:16:27]

So TypeGraphInferer.analyzeMain is not called, but compiler.disableTypeInference
is false?
That seems very odd.  

Is there something different about how the compiler (the Compiler from
compilerFor in memory_compiler.dart) is running? 
I'd rather understand what is going on with that than make this change.

Florian - any ideas?

+    if (inferrer == null) return null;
     return inferrer.types.getInferredTypeOf(element).type;
   }