Sanitize names for backing fields and private declarations in JS BE

See KT-1816

js/js.frontend/src/org/jetbrains/kotlin/js/naming/NameSuggestion.kt

@@ -322,7 +322,10 @@ class NameSuggestion {
 
         @JvmStatic fun getPrivateMangledName(baseName: String, descriptor: CallableDescriptor): String {
             val ownerName = descriptor.containingDeclaration.fqNameUnsafe.asString()
-            return getStableMangledName(baseName, ownerName + ":" + encodeSignature(descriptor))
+
+            // Base name presents here since name part gets sanitized, so we have to produce different suffixes to distinguish
+            // between, say `.` and `;`.
+            return getStableMangledName(sanitizeName(baseName), ownerName + "." + baseName + ":" + encodeSignature(descriptor))
         }
 
         fun getInternalMangledName(suggestedName: String, forCalculateId: String): String {

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

@@ -1166,6 +1166,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("peculiarName.kt")
+        public void testPeculiarName() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/delegateProperty/peculiarName.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("propertyMetadata.kt")
         public void testPropertyMetadata() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/delegateProperty/propertyMetadata.kt");
@@ -2536,6 +2542,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("privateDeclarations.kt")
+            public void testPrivateDeclarations() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/expression/identifierClash/privateDeclarations.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("useVariableOfNameOfFunction.kt")
             public void testUseVariableOfNameOfFunction() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/expression/identifierClash/useVariableOfNameOfFunction.kt");

js/js.translator/testData/box/delegateProperty/peculiarName.kt

@@ -0,0 +1,25 @@
+// EXPECTED_REACHABLE_NODES: 1006
+class X(private val x: String) {
+    operator fun getValue(thisRef: Any?, property: Any): String = x
+}
+
+class C {
+    @JsName("a") val `;`: String by X("foo")
+
+    private val `.`: String by X("bar")
+
+    private val `@`: String by X("baz")
+
+    fun bar(): String = `.`
+
+    fun baz(): String = `@`
+}
+
+fun box(): String {
+    val c = C()
+    if (c.`;` != "foo") return "fail1: ${c.`;`}"
+    if (c.bar() != "bar") return "fail2: ${c.bar()}"
+    if (c.baz() != "baz") return "fail3: ${c.baz()}"
+
+    return "OK"
+}

js/js.translator/testData/box/expression/identifierClash/privateDeclarations.kt

@@ -0,0 +1,17 @@
+// EXPECTED_REACHABLE_NODES: 1000
+open class A {
+    private val `.` = "A"
+    private val `;` = "B"
+
+    private fun `@`() = "C"
+    private fun `#`() = "D"
+
+    fun foo() = `.` + `;` + `@`() + `#`()
+}
+
+fun box(): String {
+    val x = A().foo()
+    if (x != "ABCD") return "fail: $x"
+
+    return "OK"
+}