[JS IR BE] Make backend be able work with unbound symbols

* Fix array type deserialization
 * Prepare to compilation against klibs

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/descriptors/IrBuiltIns.kt

@@ -96,8 +96,8 @@ class IrBuiltIns(
         builtIns.nothing to IrTypeMapper({ nothingType }, { nothingNType }),
         builtIns.unit to IrTypeMapper({ unitType }, { buildNullableType(unitType) }),
         builtIns.string to IrTypeMapper({ stringType }, { buildNullableType(stringType) }),
-        builtIns.throwable to IrTypeMapper({ throwableType }, { buildNullableType(throwableType) }),
-        builtIns.array to IrTypeMapper({ arrayType }, { buildNullableType(arrayType) })
+        builtIns.throwable to IrTypeMapper({ throwableType }, { buildNullableType(throwableType) })//,
+//        builtIns.array to IrTypeMapper({ arrayType }, { buildNullableType(arrayType) })
     )
 
     fun getPrimitiveTypeOrNullByDescriptor(descriptor: ClassifierDescriptor, isNullable: Boolean) =

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/ExternalDependenciesGenerator.kt

@@ -61,7 +61,7 @@ class ExternalDependenciesGenerator(
 
             deserializer?.declareForwardDeclarations()
 
-            assert(symbolTable.unboundClasses.isEmpty())
+//            assert(symbolTable.unboundClasses.isEmpty())
             assert(symbolTable.unboundConstructors.isEmpty())
             assert(symbolTable.unboundEnumEntries.isEmpty())
             assert(symbolTable.unboundFields.isEmpty())