[builtins] Fixed a Gcc compilation error in src/code-stub-assembler.cc.

src/code-stub-assembler.cc

Index: src/code-stub-assembler.cc
diff --git a/src/code-stub-assembler.cc b/src/code-stub-assembler.cc
index 1a1ce3944396390e35c23fdf530f27bff9f656d5..e44e52f428419b0f46d7541ae56978ac10ff0aee 100644
--- a/src/code-stub-assembler.cc
+++ b/src/code-stub-assembler.cc
@@ -7906,7 +7906,7 @@ compiler::Node* CodeStubAssembler::NumberInc(compiler::Node* value) {
 compiler::Node* CodeStubAssembler::CreateArrayIterator(
     compiler::Node* array, compiler::Node* array_map,
     compiler::Node* array_type, compiler::Node* context, IterationKind mode) {
-  int kBaseMapIndex;
+  int kBaseMapIndex = 0;
   switch (mode) {
     case IterationKind::kKeys:
       kBaseMapIndex = Context::TYPED_ARRAY_KEY_ITERATOR_MAP_INDEX;