[turbofan] remove dependence of InstructionBlock on BasicBlock

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 d27519a9060c99da77d0967a0c35d57f57dd3f16..51522bd8c03534113ce48d6f178499e1e67cfdf4 100644
--- a/src/compiler/register-allocator.cc
+++ b/src/compiler/register-allocator.cc
@@ -1706,8 +1706,7 @@ void RegisterAllocator::BuildLiveRanges() {
   // Process the blocks in reverse order.
   for (int block_id = code()->InstructionBlockCount() - 1; block_id >= 0;
        --block_id) {
-    auto block =
-        code()->InstructionBlockAt(BasicBlock::RpoNumber::FromInt(block_id));
+    auto block = code()->InstructionBlockAt(RpoNumber::FromInt(block_id));
     auto live = ComputeLiveOut(block);
     // Initially consider all live_out values live for the entire block. We
     // will shorten these intervals if necessary.