Cosmetic changes ("set up" is a verb, "setup" is a noun).

src/arm/macro-assembler-arm.h

Index: src/arm/macro-assembler-arm.h
===================================================================
--- src/arm/macro-assembler-arm.h	(revision 10367)
+++ src/arm/macro-assembler-arm.h	(working copy)
@@ -508,7 +508,7 @@
   // ---------------------------------------------------------------------------
   // JavaScript invokes
 
-  // Setup call kind marking in ecx. The method takes ecx as an
+  // Set up call kind marking in ecx. The method takes ecx as an
   // explicit first parameter to make the code more readable at the
   // call sites.
   void SetCallKind(Register dst, CallKind kind);