dart2js cps_ir: Use interceptors for is-checks (version 2)

pkg/compiler/lib/src/tree_ir/optimization/logical_rewriter.dart

Index: pkg/compiler/lib/src/tree_ir/optimization/logical_rewriter.dart
diff --git a/pkg/compiler/lib/src/tree_ir/optimization/logical_rewriter.dart b/pkg/compiler/lib/src/tree_ir/optimization/logical_rewriter.dart
index bc49dc750fd47f5d27e7d8f210fd3d9f9ac60764..4f0be4ad41428b4d8f3bb5a075004aaa377178a1 100644
--- a/pkg/compiler/lib/src/tree_ir/optimization/logical_rewriter.dart
+++ b/pkg/compiler/lib/src/tree_ir/optimization/logical_rewriter.dart
@@ -335,8 +335,13 @@ class LogicalRewriter extends RecursiveTransformer
     return isTrue(e) ||
            isFalse(e) ||
            e is Not ||
-           e is LogicalOperator ||
-           e is ApplyBuiltinOperator && operatorReturnsBool(e.operator);
+           e is LogicalOperator && isBooleanValuedLogicalOperator(e) ||
+           e is ApplyBuiltinOperator && operatorReturnsBool(e.operator) ||
+           e is TypeOperator && isBooleanValuedTypeOperator(e);
+  }
+
+  bool isBooleanValuedLogicalOperator(LogicalOperator e) {
+    return isBooleanValued(e.left) && isBooleanValued(e.right);
   }
 
   /// True if the given operator always returns `true` or `false`.
@@ -361,6 +366,10 @@ class LogicalRewriter extends RecursiveTransformer
     }
   }
 
+  bool isBooleanValuedTypeOperator(TypeOperator e) {
+    return e.isTypeTest;
+  }
+
   BuiltinOperator negateBuiltin(BuiltinOperator operator) {
     switch (operator) {
       case BuiltinOperator.StrictEq: return BuiltinOperator.StrictNeq;
@@ -552,4 +561,3 @@ class LogicalRewriter extends RecursiveTransformer
     --node.variable.readCount;
   }
 }
-