Allow Turbofan optimization of Ignition generators

src/compiler/register-allocator.cc

Index: src/compiler/register-allocator.cc
diff --git a/src/compiler/register-allocator.cc b/src/compiler/register-allocator.cc
index d3e6c26db1976245e91916158c63b7fd25c540c6..0cc4572279323c6bbd68a7d72deb9e9372998522 100644
--- a/src/compiler/register-allocator.cc
+++ b/src/compiler/register-allocator.cc
@@ -3088,7 +3088,7 @@ bool LinearScanAllocator::TryReuseSpillForPhi(TopLevelLiveRange* range) {
             ? range->TopLevel()->GetSpillRange()
             : data()->AssignSpillRangeToLiveRange(range->TopLevel());
     bool merged = first_op_spill->TryMerge(spill_range);
-    CHECK(merged);
+    if (!merged) return false;
     Spill(range);
     return true;
   } else if (pos->pos() > range->Start().NextStart()) {
@@ -3097,7 +3097,7 @@ bool LinearScanAllocator::TryReuseSpillForPhi(TopLevelLiveRange* range) {
             ? range->TopLevel()->GetSpillRange()
             : data()->AssignSpillRangeToLiveRange(range->TopLevel());
     bool merged = first_op_spill->TryMerge(spill_range);
-    CHECK(merged);
+    if (!merged) return false;
     SpillBetween(range, range->Start(), pos->pos());
     DCHECK(UnhandledIsSorted());
     return true;