Reland "Record the arguments for CreateArrayComp correctly as arguments.".

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 10878)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -997,7 +997,7 @@
 void CreateArrayComp::EmitNativeCode(FlowGraphCompiler* compiler) {
   // Allocate the array.  R10 = length, RBX = element type.
   ASSERT(locs()->in(0).reg() == RBX);
-  __ movq(R10, Immediate(Smi::RawValue(ElementCount())));
+  __ movq(R10, Immediate(Smi::RawValue(ArgumentCount())));
   compiler->GenerateCall(token_pos(),
                          try_index(),
                          &StubCode::AllocateArrayLabel(),
@@ -1007,8 +1007,8 @@
 
   // Pop the element values from the stack into the array.
   __ leaq(R10, FieldAddress(RAX, Array::data_offset()));
-  for (int i = ElementCount() - 1; i >= 0; --i) {
-    ASSERT(ElementAt(i)->IsUse());
+  for (int i = ArgumentCount() - 1; i >= 0; --i) {
+    ASSERT(ArgumentAt(i)->value()->IsUse());
     __ popq(Address(R10, i * kWordSize));
   }
 }