[turbofan] Eliminate usage of representation dimension of Type.

test/cctest/compiler/test-representation-change.cc

Index: test/cctest/compiler/test-representation-change.cc
diff --git a/test/cctest/compiler/test-representation-change.cc b/test/cctest/compiler/test-representation-change.cc
index ce3564301c393ccd46f19501dba34e5faa0b7057..242793340ea809fd3f2ac78040b2266b31912871 100644
--- a/test/cctest/compiler/test-representation-change.cc
+++ b/test/cctest/compiler/test-representation-change.cc
@@ -525,15 +525,11 @@ TEST(SingleChanges) {
               Type::Unsigned32(), MachineRepresentation::kWord32);
   CheckChange(IrOpcode::kChangeTaggedToFloat64, MachineRepresentation::kTagged,
               Type::Number(), MachineRepresentation::kFloat64);
-  CheckChange(IrOpcode::kChangeTaggedToFloat64, MachineRepresentation::kTagged,
-              Type::Number(), MachineRepresentation::kFloat64);
   CheckChange(IrOpcode::kTruncateTaggedToFloat64,
               MachineRepresentation::kTagged, Type::NumberOrUndefined(),
               MachineRepresentation::kFloat64);
-  CheckTwoChanges(IrOpcode::kChangeTaggedSignedToInt32,
-                  IrOpcode::kChangeInt32ToFloat64,
-                  MachineRepresentation::kTagged, Type::TaggedSigned(),
-                  MachineRepresentation::kFloat64);
+  CheckChange(IrOpcode::kChangeTaggedToFloat64, MachineRepresentation::kTagged,
+              Type::Signed31(), MachineRepresentation::kFloat64);
 
   // Int32,Uint32 <-> Float64 are actually machine conversions.
   CheckChange(IrOpcode::kChangeInt32ToFloat64, MachineRepresentation::kWord32,