Minor. Remove UNREACHABLE_CODE slice from BindingContext

There was no reading from that slice, so it is redundant

compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowInformationProvider.kt

@@ -279,7 +279,6 @@ class ControlFlowInformationProvider private constructor(
     private fun reportUnreachableCode(unreachableCode: UnreachableCode) {
         for (element in unreachableCode.elements) {
             trace.report(Errors.UNREACHABLE_CODE.on(element, unreachableCode.getUnreachableTextRanges(element)))
-            trace.record(BindingContext.UNREACHABLE_CODE, element, true)
         }
     }
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/BindingContext.java

@@ -172,7 +172,6 @@ public interface BindingContext {
     // use extension element.isUsedAsExpression() instead
     WritableSlice<KtElement, Boolean> USED_AS_EXPRESSION = Slices.createSimpleSetSlice();
     WritableSlice<KtElement, Boolean> USED_AS_RESULT_OF_LAMBDA = Slices.createSimpleSetSlice();
-    WritableSlice<KtElement, Boolean> UNREACHABLE_CODE = Slices.createSimpleSetSlice();
 
     WritableSlice<VariableDescriptor, CaptureKind> CAPTURED_IN_CLOSURE = new BasicWritableSlice<>(DO_NOTHING);
     WritableSlice<KtDeclaration, PreliminaryDeclarationVisitor> PRELIMINARY_VISITOR = new BasicWritableSlice<>(DO_NOTHING);