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

src/ast/ast.h

Index: src/ast/ast.h
diff --git a/src/ast/ast.h b/src/ast/ast.h
index c66055e2952c4d6a993ed0bc36d0db65c450b4f1..dec29e421f7b2edd8f90acff4e4a24a4733cd9f8 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -1790,15 +1790,6 @@ class Call final : public Expression {
     return !target_.is_null();
   }
 
-  bool global_call() const {
-    VariableProxy* proxy = expression_->AsVariableProxy();
-    return proxy != NULL && proxy->var()->IsUnallocatedOrGlobalSlot();
-  }
-
-  bool known_global_function() const {
-    return global_call() && !target_.is_null();
-  }
-
   Handle<JSFunction> target() { return target_; }
 
   Handle<AllocationSite> allocation_site() { return allocation_site_; }