Slightly refactor module dependencies of backend.js/serialization.js

The comment in serialization.js/build.gradle.kts is not needed because
such dependency cannot be introduced accidentally, since Gradle does not
support cycles in module dependencies.

compiler/ir/backend.js/build.gradle.kts

@@ -8,7 +8,6 @@ dependencies {
     compile(project(":compiler:frontend"))
     compile(project(":compiler:backend-common"))
     compile(project(":compiler:ir.tree"))
-    compile(project(":compiler:ir.psi2ir"))
     compile(project(":compiler:ir.backend.common"))
     compile(project(":compiler:ir.serialization.common"))
     compile(project(":compiler:ir.serialization.js"))