[base] Move hashmap allocator to a field

src/ast/scopes.cc

Index: src/ast/scopes.cc
diff --git a/src/ast/scopes.cc b/src/ast/scopes.cc
index d45b02091cd805d1b0e5ec8fad07f651cac2ca7b..b53382598ab1815abf6810c356bbf467fdcee570 100644
--- a/src/ast/scopes.cc
+++ b/src/ast/scopes.cc
@@ -36,9 +36,8 @@ Variable* VariableMap::Declare(Zone* zone, Scope* scope,
   // AstRawStrings are unambiguous, i.e., the same string is always represented
   // by the same AstRawString*.
   // FIXME(marja): fix the type of Lookup.
-  Entry* p =
-      ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->hash(),
-                                  ZoneAllocationPolicy(zone));
+  Entry* p = ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name),
+                                         name->hash());
   if (added) *added = p->value == nullptr;
   if (p->value == nullptr) {
     // The variable has not been declared yet -> insert it.
@@ -56,9 +55,8 @@ void VariableMap::Remove(Variable* var) {
 
 void VariableMap::Add(Zone* zone, Variable* var) {
   const AstRawString* name = var->raw_name();
-  Entry* p =
-      ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->hash(),
-                                  ZoneAllocationPolicy(zone));
+  Entry* p = ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name),
+                                         name->hash());
   DCHECK_NULL(p->value);
   DCHECK_EQ(name, p->key);
   p->value = var;
@@ -81,9 +79,8 @@ void SloppyBlockFunctionMap::Declare(Zone* zone, const AstRawString* name,
                                      SloppyBlockFunctionStatement* stmt) {
   // AstRawStrings are unambiguous, i.e., the same string is always represented
   // by the same AstRawString*.
-  Entry* p =
-      ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->hash(),
-                                  ZoneAllocationPolicy(zone));
+  Entry* p = ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name),
+                                         name->hash());
   stmt->set_next(static_cast<SloppyBlockFunctionStatement*>(p->value));
   p->value = stmt;
 }