Only run library converter once.

Change-Id: I6e0b8c7f8b2bc7c6a399d5dc58332b5a75bf5104
diff --git a/src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java b/src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java
index f3dd806..028a397 100644
--- a/src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java
+++ b/src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java
@@ -1344,7 +1344,8 @@
     previous = printMethod(code, "IR after interface method rewriting (SSA)", previous);
 
     // This pass has to be after interfaceMethodRewriter and BackportedMethodRewriter.
-    if (desugaredLibraryAPIConverter != null) {
+    if (desugaredLibraryAPIConverter != null
+        && (!appView.enableWholeProgramOptimizations() || methodProcessor.isPrimary())) {
       desugaredLibraryAPIConverter.desugar(code);
       assert code.isConsistentSSA();
     }