Revert "Implement subclass union and intersection on type mask."

sdk/lib/_internal/compiler/implementation/ssa/types.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/types.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/types.dart b/sdk/lib/_internal/compiler/implementation/ssa/types.dart
index ec73cb0e10ab4a4bad03bc0ae7b11b1401012ee6..578654db78e7211bcb24c70ffdca2d30edc0b258 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/types.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/types.dart
@@ -978,7 +978,7 @@ class HBoundedType extends HType {
 
     TypeMask otherMask = other.computeMask(compiler);
     if (otherMask != null) {
-      TypeMask intersection = mask.intersection(otherMask, compiler);
+      TypeMask intersection = mask.intersection(otherMask, compiler.types);
       if (intersection != null) {
         if (intersection == mask) return this;
         return new HType.fromMask(intersection, compiler);
@@ -1002,7 +1002,7 @@ class HBoundedType extends HType {
 
     TypeMask otherMask = other.computeMask(compiler);
     if (otherMask != null) {
-      TypeMask union = mask.union(otherMask, compiler);
+      TypeMask union = mask.union(otherMask, compiler.types);
       if (union == null) return HType.UNKNOWN;
       if (union == mask) return this;
       return new HType.fromMask(union, compiler);