Add module name as a prefix to declaration keys in JS translator

This is necessary due to different modules can have same
package declarations. When importing declarations from these
packages, we should distinguish from which module we are importing it.

See KT-18652

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java

@@ -5618,6 +5618,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("samePackageNames.kt")
+        public void testSamePackageNames() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/multiModule/samePackageNames.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("useElementsFromDefaultPackageInAnotherModule.kt")
         public void testUseElementsFromDefaultPackageInAnotherModule() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/multiModule/useElementsFromDefaultPackageInAnotherModule.kt");

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/signatureUtils.kt

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.js.translate.utils
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.js.naming.encodeSignature
 import org.jetbrains.kotlin.resolve.DescriptorUtils
+import org.jetbrains.kotlin.resolve.descriptorUtil.module
 
 // Unfortunately, our descriptor serializer can't serialize references to descriptors.
 // We have to serialize entire class or package to serialize function or property.
@@ -50,7 +51,9 @@ fun generateSignature(descriptor: DeclarationDescriptor): String? {
             parent + separator + escape(descriptor.name.asString()) + "|" + encodeSignature(descriptor)
         }
         is PackageFragmentDescriptor -> {
-            if (descriptor.fqName.isRoot) "" else escape(descriptor.fqName.pathSegments().map { escape(it.identifier) }.joinToString("."))
+            val module = descriptor.module.name.asString()
+            val parts = sequenceOf(module) + descriptor.fqName.pathSegments().map { it.identifier }
+            parts.joinToString(".") { escape(it) }
         }
         is ClassDescriptor -> {
             val parent = generateSignature(descriptor.containingDeclaration) ?: return null

js/js.translator/testData/box/multiModule/samePackageNames.kt

@@ -0,0 +1,54 @@
+// EXPECTED_REACHABLE_NODES: 511
+// MODULE: lib1
+// FILE: lib1.kt
+package pkg
+
+object O {
+    fun f() = "O.f"
+}
+
+fun foo() = "foo"
+
+class A {
+    fun f() = "A.f"
+}
+
+// MODULE: lib2
+// FILE: lib2.kt
+package pkg
+
+object P {
+    fun f() = "P.f"
+}
+
+fun bar() = "bar"
+
+class B {
+    fun f() = "B.f"
+}
+
+// MODULE: main(lib1, lib2)
+// FILE: main.kt
+import pkg.*
+
+fun box(): String {
+    var r = O.f()
+    if (r != "O.f") return "fail1: $r"
+
+    r = foo()
+    if (r != "foo") return "fail2: $r"
+
+    r = A().f()
+    if (r != "A.f") return "fail3: $r"
+
+    r = P.f()
+    if (r != "P.f") return "fail4: $r"
+
+    r = bar()
+    if (r != "bar") return "fail5: $r"
+
+    r = B().f()
+    if (r != "B.f") return "fail6: $r"
+
+    return "OK"
+}