VM: Replace CheckedHandle with Cast/Handle in some places.

runtime/vm/dart_entry.cc

Index: runtime/vm/dart_entry.cc
diff --git a/runtime/vm/dart_entry.cc b/runtime/vm/dart_entry.cc
index 82055bb7b89f2531f6e63add2ff149d3fee6b3e5..fdb1ce1dd64d703aeb51e3675fdcf05c79de2188 100644
--- a/runtime/vm/dart_entry.cc
+++ b/runtime/vm/dart_entry.cc
@@ -249,12 +249,12 @@ ArgumentsDescriptor::ArgumentsDescriptor(const Array& array)
 
 
 intptr_t ArgumentsDescriptor::Count() const {
-  return Smi::CheckedHandle(array_.At(kCountIndex)).Value();
+  return Smi::Cast(Object::Handle(array_.At(kCountIndex))).Value();
 }
 
 
 intptr_t ArgumentsDescriptor::PositionalCount() const {
-  return Smi::CheckedHandle(array_.At(kPositionalCountIndex)).Value();
+  return Smi::Cast(Object::Handle(array_.At(kPositionalCountIndex))).Value();
 }