add TARGET_BACKEND: JVM to some decompiled tests

idea/testData/decompiler/decompiledText/DependencyOnNestedClasses/directives.txt

@@ -0,0 +1,4 @@
+// TODO Remove this restriction when nested classes will be supported in js backend.
+// See KT-1907 Support nested classes in js-backend
+// https://youtrack.jetbrains.com/issue/KT-1907
+// TARGET_BACKEND: JVM

idea/testData/decompiler/decompiledText/FlexibleTypes/directives.txt

@@ -0,0 +1 @@
+// TARGET_BACKEND: JVM

idea/testData/decompiler/decompiledText/NestedClasses/directives.txt

@@ -0,0 +1,4 @@
+// TODO Remove this restriction when nested classes will be supported in js backend.
+// See KT-1907 Support nested classes in js-backend
+// https://youtrack.jetbrains.com/issue/KT-1907
+// TARGET_BACKEND: JVM

idea/testData/decompiler/decompiledText/SecondaryConstructors/directives.txt

@@ -0,0 +1,4 @@
+// TODO Remove this restriction when secondary constructors will be supported in js backend.
+// See KT-7798 JS: add support for secondary constructors
+// https://youtrack.jetbrains.com/issue/KT-7798
+// TARGET_BACKEND: JVM