[turbofan] Add SimplifiedOperator::Allocate operator.

src/compiler/access-builder.h

Index: src/compiler/access-builder.h
diff --git a/src/compiler/access-builder.h b/src/compiler/access-builder.h
index 76f1d8ad15f22469c1e1a96ba1956622a91f8484..ea084a2061c1274d7d4f1815bb69d84d9d1cd91d 100644
--- a/src/compiler/access-builder.h
+++ b/src/compiler/access-builder.h
@@ -31,6 +31,9 @@ class AccessBuilder final : public AllStatic {
   // Provides access to JSArrayBuffer::backing_store() field.
   static FieldAccess ForJSArrayBufferBackingStore();
 
+  // Provides access to FixedArray::length() field.
+  static FieldAccess ForFixedArrayLength();
+
   // Provides access to ExternalArray::external_pointer() field.
   static FieldAccess ForExternalArrayPointer();