Fix #6152: Dotty tries to override Java bridge methods

Dotty overrides Java bridge methods when the user intends to override
the method for which the bridge was generated. This commit forbids
Dotty to override bridge methods altogether.

Author: anatoliykmetyuk

compiler/src/dotty/tools/dotc/transform/OverridingPairs.scala

@@ -39,8 +39,9 @@ object OverridingPairs {
      *  Types always match. Term symbols match if their membertypes
      *  relative to <base>.this do
      */
-    protected def matches(sym1: Symbol, sym2: Symbol): Boolean =
-      sym1.isType || self.memberInfo(sym1).matches(self.memberInfo(sym2))
+    protected def matches(sym1: Symbol, sym2: Symbol): Boolean = {
+      sym1.isType || (!sym2.is(Bridge) && self.memberInfo(sym1).matches(self.memberInfo(sym2)))
+    }
 
     /** The symbols that can take part in an overriding pair */
     private val decls = {