Fix typos spotted by Andreas.

Change-Id: I564b4bc5995d91f4c6c4e4f2427ed7c279cb8740
diff --git a/compiler/optimizing/intrinsics_x86_64.cc b/compiler/optimizing/intrinsics_x86_64.cc
index e4f2518..05ea906 100644
--- a/compiler/optimizing/intrinsics_x86_64.cc
+++ b/compiler/optimizing/intrinsics_x86_64.cc
@@ -681,7 +681,7 @@
   X86_64Assembler* assembler = GetAssembler();
   LocationSummary* locations = invoke->GetLocations();
 
-  // Note that the null check must have be done earlier.
+  // Note that the null check must have been done earlier.
   DCHECK(!invoke->CanDoImplicitNullCheck());
 
   CpuRegister argument = locations->InAt(1).AsRegister<CpuRegister>();