Remove old code for jstype.

Change-Id: Ib26c1ef6cccd8657f48a5863ef167396f3f1d6ab

dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java

diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java
index 8615cae..f168d42 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java
@@ -92,7 +92,7 @@
 
   @Override
   public boolean canBeImplementedExternally() {
-    return isJsNative() || isJsFunctionMethod() || isJsInterfaceMethod();
+    return isJsNative() || isJsFunctionMethod();
   }
 
   /**
@@ -153,10 +153,6 @@
     params = Lists.add(params, x);
   }
 
-  private boolean isJsInterfaceMethod() {
-    return isInterfaceMethod() && enclosingType.isJsType();
-  }
-
   private boolean isInterfaceMethod() {
     return enclosingType instanceof JInterfaceType;
   }
@@ -317,6 +313,7 @@
     this.preventDevirtualization = true;
   }
 
+  @Override
   public boolean isJsMethodVarargs() {
     if (getParams().isEmpty() || !(canBeReferencedExternally() || canBeImplementedExternally())) {
       return false;