Only reference constant root list entries in the snapshot.

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index 2051974171d6c5a2ed8b510055d7809f5ea7bd76..06bfe3c1cec810019d20ede859963ffd0261323a 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -439,6 +439,7 @@ void MacroAssembler::LoadRoot(Register destination,
 void MacroAssembler::StoreRoot(Register source,
                                Heap::RootListIndex index,
                                Condition cond) {
+  DCHECK(Heap::RootCanBeWrittenAfterInitialization(index));
   str(source, MemOperand(kRootRegister, index << kPointerSizeLog2), cond);
 }