Issue 6836. Reference to prefixed undeclared identifier in static context is also warning

compiler/java/com/google/dart/compiler/resolver/ResolverErrorCode.java

Index: compiler/java/com/google/dart/compiler/resolver/ResolverErrorCode.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/ResolverErrorCode.java b/compiler/java/com/google/dart/compiler/resolver/ResolverErrorCode.java
index ebe4554b7fe007aa8ffe673653dcd9e813045344..c2cefc944f1762f336078100287fefffe663214c 100644
--- a/compiler/java/com/google/dart/compiler/resolver/ResolverErrorCode.java
+++ b/compiler/java/com/google/dart/compiler/resolver/ResolverErrorCode.java
@@ -24,7 +24,7 @@ public enum ResolverErrorCode implements ErrorCode {
   CANNOT_ASSIGN_TO_METHOD(ErrorSeverity.WARNING, "cannot assign value to method '%s'."),
   CANNOT_BE_RESOLVED("cannot resolve %s"),
   // TODO(zundel): error message needs JUnit test - how to test #imports in junit?
-  CANNOT_BE_RESOLVED_LIBRARY("cannot resolve %s in library %s"),
+  CANNOT_BE_RESOLVED_LIBRARY(ErrorSeverity.WARNING, "cannot resolve %s in library %s"),
   CANNOT_CALL_FUNCTION_TYPE_ALIAS("Function type aliases cannot be called"),
   // TODO(zundel): error message needs JUnit test - how to test #imports in junit?
   CANNOT_CALL_LIBRARY_PREFIX("Library prefixes cannot be called"),