Get rid of some downcasts

runtime/bin/filter.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/dartutils.h"
 #include "bin/filter.h"
 #include "bin/io_buffer.h"
 
 #include "include/dart_api.h"
 
@@ skipping 64 matching lines @@
   if (Dart_IsError(result)) {
     delete filter;
     Dart_PropagateError(result);
   }
 }
 
 void FUNCTION_NAME(Filter_Process)(Dart_NativeArguments args) {
   Dart_Handle filter_obj = Dart_GetNativeArgument(args, 0);
   Filter* filter = GetFilter(filter_obj);
   Dart_Handle data_obj = Dart_GetNativeArgument(args, 1);
-  intptr_t start = DartUtils::GetIntegerValue(Dart_GetNativeArgument(args, 2));
-  intptr_t end = DartUtils::GetIntegerValue(Dart_GetNativeArgument(args, 3));
+  intptr_t start = DartUtils::GetIntptrValue(Dart_GetNativeArgument(args, 2));
+  intptr_t end = DartUtils::GetIntptrValue(Dart_GetNativeArgument(args, 3));
   intptr_t chunk_length = end - start;
   intptr_t length;
   Dart_TypedData_Type type;
   uint8_t* buffer = NULL;
   Dart_Handle result = Dart_TypedDataAcquireData(
       data_obj, &type, reinterpret_cast<void**>(&buffer), &length);
   if (!Dart_IsError(result)) {
     uint8_t* zlib_buffer = new uint8_t[chunk_length];
     if (zlib_buffer == NULL) {
       Dart_TypedDataReleaseData(data_obj);
@@ skipping 207 matching lines @@
     case Z_STREAM_ERROR:
       // An error occoured.
       delete[] current_buffer_;
       current_buffer_ = NULL;
       return -1;
   }
 }
 
 }  // namespace bin
 }  // namespace dart