Fix an overflow in on-stack replacement spill-slot allocation for Crankshaft.

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index f5304287bb53bbfd53bbed8e6add644e6707681b..10c66624b702d5968fbd7d321871335c56611ad2 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -2120,6 +2120,9 @@ LInstruction* LChunkBuilder::DoParameter(HParameter* instr) {
 
 LInstruction* LChunkBuilder::DoUnknownOSRValue(HUnknownOSRValue* instr) {
   int spill_index = chunk()->GetNextSpillIndex(false);  // Not double-width.
+  if (spill_index > LUnallocated::kMaxFixedIndex) {
+    Abort("Too many spill slots needed for OSR");
+  }
   return DefineAsSpilled(new LUnknownOSRValue, spill_index);
 }