Make allocation of Dart parameters and local variables architecture independent.

runtime/vm/flow_graph_builder.cc

Index: runtime/vm/flow_graph_builder.cc
===================================================================
--- runtime/vm/flow_graph_builder.cc	(revision 20045)
+++ runtime/vm/flow_graph_builder.cc	(working copy)
@@ -2876,10 +2876,10 @@
       const Function& function = owner()->parsed_function().function();
       int num_params = function.NumParameters();
       int param_frame_index = (num_params == function.num_fixed_parameters()) ?
-          (1 + num_params) : ParsedFunction::kFirstLocalSlotIndex;
+          (kLastParamSlotIndex + num_params - 1) : kFirstLocalSlotIndex;
       // Handle the saved arguments descriptor as an additional parameter.
       if (owner()->parsed_function().GetSavedArgumentsDescriptorVar() != NULL) {
-        ASSERT(param_frame_index == ParsedFunction::kFirstLocalSlotIndex);
+        ASSERT(param_frame_index == kFirstLocalSlotIndex);
         num_params++;
       }
       for (int pos = 0; pos < num_params; param_frame_index--, pos++) {