Extract hardcoded error strings into a single place and replace them with enum.

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index a5371f7d67334fffd712fd6ac672e1b842709a10..b68b52f63a4cd3e154e0f2b31b498359d89f0d34 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -442,7 +442,7 @@ LPlatformChunk* LChunkBuilder::Build() {
 }
 
 
-void LCodeGen::Abort(const char* reason) {
+void LCodeGen::Abort(BailoutReason reason) {
   info()->set_bailout_reason(reason);
   status_ = ABORTED;
 }
@@ -650,7 +650,7 @@ LUnallocated* LChunkBuilder::TempRegister() {
       new(zone()) LUnallocated(LUnallocated::MUST_HAVE_REGISTER);
   int vreg = allocator_->GetVirtualRegister();
   if (!allocator_->AllocationOk()) {
-    Abort("Out of virtual registers while trying to allocate temp register.");
+    Abort(kOutOfVirtualRegistersWhileTryingToAllocateTempRegister);
     vreg = 0;
   }
   operand->set_virtual_register(vreg);
@@ -2365,7 +2365,7 @@ LInstruction* LChunkBuilder::DoParameter(HParameter* instr) {
 LInstruction* LChunkBuilder::DoUnknownOSRValue(HUnknownOSRValue* instr) {
   int spill_index = chunk()->GetNextSpillIndex(false);  // Not double-width.
   if (spill_index > LUnallocated::kMaxFixedSlotIndex) {
-    Abort("Too many spill slots needed for OSR");
+    Abort(kTooManySpillSlotsNeededForOSR);
     spill_index = 0;
   }
   return DefineAsSpilled(new(zone()) LUnknownOSRValue, spill_index);