Reduce use of getClosureInfoForMember and cleanup closure_test

pkg/compiler/lib/src/js_model/closure.dart

Index: pkg/compiler/lib/src/js_model/closure.dart
diff --git a/pkg/compiler/lib/src/js_model/closure.dart b/pkg/compiler/lib/src/js_model/closure.dart
index f54d8e77dd9b8c930a34e64368080c6230a3d636..f14bb556dc1315fca5a3e50218d3cfa42ffdacc6 100644
--- a/pkg/compiler/lib/src/js_model/closure.dart
+++ b/pkg/compiler/lib/src/js_model/closure.dart
@@ -165,7 +165,10 @@ class KernelClosureConversionTask extends ClosureConversionTask<ir.Node> {
       entity = constructorBody.constructor;
     }
 
-    return _scopeMap[entity] ?? getClosureInfoForMember(entity);
+    ScopeInfo scopeInfo = _scopeMap[entity];
+    assert(
+        scopeInfo != null, failedAt(entity, "Missing scope info for $entity."));
+    return scopeInfo;
   }
 
   // TODO(efortuna): Eventually capturedScopesMap[node] should always
@@ -209,17 +212,6 @@ class KernelClosureConversionTask extends ClosureConversionTask<ir.Node> {
         "Closures found for ${_localClosureRepresentationMap.keys}");
     return closure;
   }
-
-  @override
-  ClosureRepresentationInfo getClosureInfoForMemberTesting(
-      MemberEntity entity) {
-    return _memberClosureRepresentationMap[entity];
-  }
-
-  @override
-  ClosureRepresentationInfo getClosureInfoForTesting(ir.Node node) {
-    return _localClosureRepresentationMap[node];
-  }
 }
 
 class KernelScopeInfo {