Don't create light classes for platform declarations

#KT-15137 Fixed

idea/tests/org/jetbrains/kotlin/asJava/KtFileLightClassTest.kt

@@ -62,6 +62,13 @@ class KtFileLightClassTest : KotlinLightCodeInsightFixtureTestCase() {
         assertEquals(0, facadeFiles.size)
     }
 
+    fun testNoFacadeForHeaderClass() {
+        val file = myFixture.configureByText("foo.kt", "platform fun foo(): Int") as KtFile
+        assertEquals(0, file.classes.size)
+        val facadeFiles = LightClassGenerationSupport.getInstance(project).findFilesForFacade(FqName("foo.FooKt"), GlobalSearchScope.allScope(project))
+        assertEquals(0, facadeFiles.size)
+    }
+
     override fun getTestDataPath(): String? {
         return PluginTestCaseBase.getTestDataPathBase() + "/asJava/fileLightClass/"
     }

idea/tests/org/jetbrains/kotlin/asJava/LightClassFromTextTest.kt

@@ -23,7 +23,9 @@ import com.intellij.testFramework.LightProjectDescriptor
 import org.jetbrains.kotlin.idea.test.KotlinLightCodeInsightFixtureTestCase
 import org.jetbrains.kotlin.idea.test.KotlinWithJdkAndRuntimeLightProjectDescriptor
 import org.jetbrains.kotlin.idea.test.PluginTestCaseBase
+import org.jetbrains.kotlin.psi.KtClassOrObject
 import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.KtNamedFunction
 import org.jetbrains.kotlin.psi.KtPsiFactory
 
 // see KtFileLightClassTest
@@ -94,6 +96,14 @@ class LightClassFromTextTest : KotlinLightCodeInsightFixtureTestCase() {
         assertEquals(exampleClass, (f.returnType as PsiClassType).resolve())
     }
 
+    fun testHeaderDeclarations() {
+        val contextFile = myFixture.configureByText("Header.kt", "platform class Foo\n\nplatform fun foo()\n") as KtFile
+        val headerClass = contextFile.declarations.single { it is KtClassOrObject }
+        assertEquals(0, headerClass.toLightElements().size)
+        val headerFunction = contextFile.declarations.single { it is KtNamedFunction }
+        assertEquals(0, headerFunction.toLightElements().size)
+    }
+
     private fun classesFromText(text: String, fileName: String = "A.kt"): Array<out PsiClass> {
         val file = KtPsiFactory(project).createFileWithLightClassSupport(fileName, text, myFixture.file)
         val classes = file.classes