Strengthen requirements for fixed registers at calls....

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
===================================================================
--- src/x64/lithium-x64.cc	(revision 6717)
+++ src/x64/lithium-x64.cc	(working copy)
@@ -74,15 +74,13 @@
   // Call instructions can use only fixed registers as
   // temporaries and outputs because all registers
   // are blocked by the calling convention.
-  // Inputs can use either fixed register or have a short lifetime (be
-  // used at start of the instruction).
+  // Inputs must use a fixed register.
   ASSERT(Output() == NULL ||
          LUnallocated::cast(Output())->HasFixedPolicy() ||
          !LUnallocated::cast(Output())->HasRegisterPolicy());
   for (UseIterator it(this); it.HasNext(); it.Advance()) {
     LOperand* operand = it.Next();
     ASSERT(LUnallocated::cast(operand)->HasFixedPolicy() ||
-           LUnallocated::cast(operand)->IsUsedAtStart() ||
            !LUnallocated::cast(operand)->HasRegisterPolicy());
   }
   for (TempIterator it(this); it.HasNext(); it.Advance()) {