JS: fix losing lambda in inline function after incremental compilation

See KT-21493

It's hard to maintain staticRef in cached AST. In fact, we don't need
it in this optimization. We'll get excessive names in used set,
which is ok: non-function names don't matter, they'll be simply ignored.
One possible concern: there's more chance to get name same to
some function's name and it won't be removed. First, it's not fatal,
it won't break the code (but put some excessive code that will likely
be removed by DCE). Second, there's same chance of two functions
having same names, and we manage to avoid this (otherwise we'll get
many problems).

js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedFunctionDefinitions.kt

@@ -20,7 +20,7 @@ import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.js.backend.ast.metadata.isLocal
 import org.jetbrains.kotlin.js.backend.ast.metadata.staticRef
 import org.jetbrains.kotlin.js.inline.util.IdentitySet
-import org.jetbrains.kotlin.js.inline.util.collectFunctionReferencesInside
+import org.jetbrains.kotlin.js.inline.util.collectReferencedNames
 
 /**
  * Removes unused function definitions:
@@ -93,13 +93,13 @@ private class UnusedLocalFunctionsCollector(private val functions: Map<JsName, J
     }
 
     private fun processLocalFunction(name: JsName, function: JsFunction) {
-        for (referenced in collectFunctionReferencesInside(function)) {
+        for (referenced in collectReferencedNames(function)) {
             tracker.addRemovableReference(name, referenced)
         }
     }
 
     private fun processNonLocalFunction(function: JsFunction) {
-        for (referenced in collectFunctionReferencesInside(function)) {
+        for (referenced in collectReferencedNames(function)) {
             tracker.markReachable(referenced)
         }
     }

js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectUtils.kt

@@ -19,14 +19,10 @@ package org.jetbrains.kotlin.js.inline.util
 import org.jetbrains.kotlin.js.backend.JsToStringGenerationVisitor
 import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.js.backend.ast.metadata.imported
-import org.jetbrains.kotlin.js.backend.ast.metadata.staticRef
 import org.jetbrains.kotlin.js.inline.util.collectors.InstanceCollector
 import org.jetbrains.kotlin.js.translate.expression.InlineMetadata
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils
 
-fun collectFunctionReferencesInside(scope: JsNode): List<JsName> =
-        collectReferencedNames(scope).filter { it.staticRef is JsFunction }
-
 fun collectReferencedNames(scope: JsNode): Set<JsName> {
     val references = mutableSetOf<JsName>()
 

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

@@ -3803,6 +3803,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("inlineLambda.kt")
+        public void testInlineLambda() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/incremental/inlineLambda.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("jsModule.kt")
         public void testJsModule() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/incremental/jsModule.kt");

js/js.translator/testData/box/incremental/inlineLambda.kt

@@ -0,0 +1,13 @@
+// EXPECTED_REACHABLE_NODES: 1128
+// FILE: a.kt
+inline fun foo(f: () -> String): () -> String {
+    val result = f()
+    return { result }
+}
+
+
+// FILE: main.kt
+// RECOMPILE
+fun bar(f: () -> String) = foo(f)()
+
+fun box(): String = bar { "OK" }