Make DefaultInfo.default_runfiles return all runfiles if the runfiles field of DefaultInfo() was used.

RELNOTES: None.
PiperOrigin-RevId: 202192091

src/main/java/com/google/devtools/build/lib/analysis/DefaultInfo.java

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/DefaultInfo.java b/src/main/java/com/google/devtools/build/lib/analysis/DefaultInfo.java
index 4da947e..778c20b 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/DefaultInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/DefaultInfo.java
@@ -103,7 +103,13 @@
 
   @Override
   public Runfiles getDefaultRunfiles() {
-    return defaultRunfiles;
+    if (dataRunfiles == null && defaultRunfiles == null) {
+      // This supports the legacy skylark runfiles constructor -- if the 'runfiles' attribute
+      // is used, then default_runfiles will return all runfiles.
+      return runfiles;
+    } else {
+      return defaultRunfiles;
+    }
   }
 
   /**