JS backend: use special JsScope(JsDynamicScope) for names from dynamic calls instead of use containing scope to avoid the impact on local names.

js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/jsScopes.kt

@@ -22,6 +22,10 @@ public fun JsObjectScope(parent: JsScope, description: String): JsObjectScope =
 
 public class JsObjectScope(parent: JsScope, description: String, scopeId: String?) : JsScope(parent, description, scopeId)
 
+public object JsDynamicScope : JsScope(null, "Scope for dynamic declarations", null) {
+    override fun doCreateName(name: String) = JsName(this, name)
+}
+
 public class JsFunctionScope(parent: JsScope, description: String) : JsScope(parent, description, null) {
 
     private val labelScopes = Stack<LabelScope>()

js/js.tests/test/org/jetbrains/k2js/test/semantics/DynamicTestGenerated.java

@@ -120,6 +120,12 @@ public class DynamicTestGenerated extends AbstractDynamicTest {
         doTest(fileName);
     }
 
+    @TestMetadata("nameClashing.kt")
+    public void testNameClashing() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/dynamic/cases/nameClashing.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("operationsWithAssignment.kt")
     public void testOperationsWithAssignment() throws Exception {
         String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/dynamic/cases/operationsWithAssignment.kt");

js/js.translator/src/org/jetbrains/k2js/translate/context/StaticContext.java

@@ -236,9 +236,7 @@ public final class StaticContext {
                 public JsName apply(@NotNull DeclarationDescriptor descriptor) {
                     if (TasksPackage.isDynamic(descriptor)) {
                         String name = descriptor.getName().asString();
-                        JsScope scope = getEnclosingScope(descriptor);
-                        assert scope instanceof JsFunctionScope;
-                        return ((JsFunctionScope) scope).declareNameUnsafe(name);
+                        return JsDynamicScope.INSTANCE$.declareName(name);
                     }
 
                     return null;

js/js.translator/testData/dynamic/cases/nameClashing.kt

@@ -0,0 +1,26 @@
+package foo
+
+fun assertContains(expectedName: String, f: () -> Unit) {
+    val s = f.toString()
+    assertTrue(s.contains(expectedName), "\"$s\" dosn't contain \"$expectedName\"")
+}
+
+fun box(): String {
+    val d: dynamic = bar
+
+    val a = {
+        val somethingBefore = 1
+        d.somethingBefore
+    }
+
+    assertContains("var somethingBefore = 1;", a)
+
+    val b = {
+        d.somethingAfter
+        val somethingAfter = 1
+    }
+
+    assertContains("var somethingAfter = 1;", b)
+
+    return "OK"
+}