Remove hacky cast now that Copybara is updated to use GlobalFrame
(https://github.com/google/copybara/commit/77a0e68eb0b044449b412e939ad25d500d2c12d3).

RELNOTES: None
PiperOrigin-RevId: 187525928
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
index c6a4567..d4e6403 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
@@ -827,10 +827,9 @@
     }
 
     /** Inherits global bindings from the given parent Frame. */
-    public Builder setGlobals(Frame parent) {
+    public Builder setGlobals(GlobalFrame parent) {
       Preconditions.checkState(this.parent == null);
-      // TODO(nharmata): This is a hacky cast done so as to not break Copybara. Remove this.
-      this.parent = (GlobalFrame) parent;
+      this.parent = parent;
       return this;
     }