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

src/mips/assembler-mips.cc

Index: src/mips/assembler-mips.cc
===================================================================
--- src/mips/assembler-mips.cc	(revision 10367)
+++ src/mips/assembler-mips.cc	(working copy)
@@ -301,7 +301,7 @@
     own_buffer_ = false;
   }
 
-  // Setup buffer pointers.
+  // Set up buffer pointers.
   ASSERT(buffer_ != NULL);
   pc_ = buffer_;
   reloc_info_writer.Reposition(buffer_ + buffer_size, pc_);
@@ -337,7 +337,7 @@
 
 void Assembler::GetCode(CodeDesc* desc) {
   ASSERT(pc_ <= reloc_info_writer.pos());  // No overlap.
-  // Setup code descriptor.
+  // Set up code descriptor.
   desc->buffer = buffer_;
   desc->buffer_size = buffer_size_;
   desc->instr_size = pc_offset();
@@ -1970,7 +1970,7 @@
   }
   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();