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

src/arm/assembler-arm.cc

Index: src/arm/assembler-arm.cc
===================================================================
--- src/arm/assembler-arm.cc	(revision 10367)
+++ src/arm/assembler-arm.cc	(working copy)
@@ -317,7 +317,7 @@
     own_buffer_ = false;
   }
 
-  // Setup buffer pointers.
+  // Set up buffer pointers.
   ASSERT(buffer_ != NULL);
   pc_ = buffer_;
   reloc_info_writer.Reposition(buffer_ + buffer_size, pc_);
@@ -349,7 +349,7 @@
   CheckConstPool(true, false);
   ASSERT(num_pending_reloc_info_ == 0);
 
-  // Setup code descriptor.
+  // Set up code descriptor.
   desc->buffer = buffer_;
   desc->buffer_size = buffer_size_;
   desc->instr_size = pc_offset();
@@ -2446,7 +2446,7 @@
   }
   CHECK_GT(desc.buffer_size, 0);  // no overflow
 
-  // Setup new buffer.
+  // Set up new buffer.
   desc.buffer = NewArray<byte>(desc.buffer_size);
 
   desc.instr_size = pc_offset();