Replace CollectVariables with locals(), update callsites to walk locals instead

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index 85c07ea37b6db8fc5ace111bb2bac1bfccdf20e5..47529c022fdaae46a4c6736a1e30828ec21f3dfd 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -1217,7 +1217,7 @@ void FullCodeGenerator::EmitGlobalVariableLoad(VariableProxy* proxy,
                                                TypeofMode typeof_mode) {
 #ifdef DEBUG
   Variable* var = proxy->var();
-  DCHECK(var->IsUnallocatedOrGlobalSlot() ||
+  DCHECK(var->IsUnallocated() ||
          (var->IsLookupSlot() && var->mode() == DYNAMIC_GLOBAL));
 #endif
   __ Move(LoadGlobalDescriptor::SlotRegister(),
@@ -2924,7 +2924,7 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
         // "delete this" is allowed.
         bool is_this = var->is_this();
         DCHECK(is_sloppy(language_mode()) || is_this);
-        if (var->IsUnallocatedOrGlobalSlot()) {
+        if (var->IsUnallocated()) {
           __ movp(rax, NativeContextOperand());
           __ Push(ContextOperand(rax, Context::EXTENSION_INDEX));
           __ Push(var->name());