Get rid of recordSourceForSynthesized

Sam descriptors now implement a common interface
SynthesizedCallableMemberDescriptor, introduced in frontend.
BindingContext.SOURCE_DESCRIPTOR_FOR_SYNTHESIZED is no longer needed

compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -1908,7 +1908,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
         if (funDescriptor instanceof SimpleFunctionDescriptor) {
             SimpleFunctionDescriptor original = ((SimpleFunctionDescriptor) funDescriptor).getOriginal();
             if (original instanceof SamConstructorDescriptor) {
-                return invokeSamConstructor(expression, resolvedCall, ((SamConstructorDescriptor) original).getSamInterface());
+                return invokeSamConstructor(expression, resolvedCall, ((SamConstructorDescriptor) original).getBaseForSynthesized());
             }
         }
 

compiler/backend/src/org/jetbrains/jet/codegen/SamCodegenUtil.java

@@ -27,7 +27,7 @@ public class SamCodegenUtil {
     public static FunctionDescriptor getOriginalIfSamAdapter(@NotNull FunctionDescriptor fun) {
         FunctionDescriptor original = fun.getOriginal();
         if (original instanceof SamAdapterDescriptor<?>) {
-            return ((SamAdapterDescriptor) original).getDeclaration();
+            return ((SamAdapterDescriptor<?>) original).getBaseForSynthesized();
         }
 
         if (original.getKind() == CallableMemberDescriptor.Kind.FAKE_OVERRIDE) {