Fix class inliner attempt to get block from detached instruction

Change-Id: I5a318f0bc2bcfd8e31a786c4cfa76dea5792b5e3
diff --git a/src/main/java/com/android/tools/r8/ir/optimize/classinliner/InlineCandidateProcessor.java b/src/main/java/com/android/tools/r8/ir/optimize/classinliner/InlineCandidateProcessor.java
index 5f6ad1a..e653838 100644
--- a/src/main/java/com/android/tools/r8/ir/optimize/classinliner/InlineCandidateProcessor.java
+++ b/src/main/java/com/android/tools/r8/ir/optimize/classinliner/InlineCandidateProcessor.java
@@ -742,8 +742,12 @@
     Set<BasicBlock> seen = Sets.newIdentityHashSet();
     Set<Instruction> users = eligibleInstance.uniqueUsers();
     for (Instruction user : users) {
+      if (!user.hasBlock()) {
+        continue;
+      }
+
       BasicBlock block = user.getBlock();
-      if (block == null || !seen.add(block)) {
+      if (!seen.add(block)) {
         continue;
       }