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

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
===================================================================
--- src/x64/lithium-codegen-x64.cc	(revision 10367)
+++ src/x64/lithium-codegen-x64.cc	(working copy)
@@ -2636,7 +2636,7 @@
     __ call(FieldOperand(rdi, JSFunction::kCodeEntryOffset));
   }
 
-  // Setup deoptimization.
+  // Set up deoptimization.
   RecordSafepointWithLazyDeopt(instr, RECORD_SIMPLE_SAFEPOINT, 0);
 
   // Restore context.
@@ -3863,7 +3863,7 @@
     DeoptimizeIf(not_equal, instr->environment());
   }
 
-  // Setup the parameters to the stub/runtime call.
+  // Set up the parameters to the stub/runtime call.
   __ movq(rax, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
   __ push(FieldOperand(rax, JSFunction::kLiteralsOffset));
   __ Push(Smi::FromInt(instr->hydrogen()->literal_index()));
@@ -3964,7 +3964,7 @@
   Handle<FixedArray> constant_properties =
       instr->hydrogen()->constant_properties();
 
-  // Setup the parameters to the stub/runtime call.
+  // Set up the parameters to the stub/runtime call.
   __ movq(rax, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
   __ push(FieldOperand(rax, JSFunction::kLiteralsOffset));
   __ Push(Smi::FromInt(instr->hydrogen()->literal_index()));