Revert "[WASM] Remove deprecated usage of externref"

This reverts commit 270a41a2db.

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/DeclarationGenerator.kt

@@ -450,6 +450,7 @@ fun generateDefaultInitializerForType(type: WasmType, g: WasmExpressionBuilder)
     WasmF64 -> g.buildConstF64(0.0)
     is WasmRefNullType -> g.buildRefNull(type.heapType)
     is WasmAnyRef -> g.buildRefNull(WasmHeapType.Simple.Any)
+    is WasmExternRef -> g.buildRefNull(WasmHeapType.Simple.Extern)
     WasmUnreachableType -> error("Unreachable type can't be initialized")
     else -> error("Unknown value type ${type.name}")
 }

wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/Types.kt

@@ -22,7 +22,8 @@ object WasmV128 : WasmType("v128", -0x5)
 object WasmI8 : WasmType("i8", -0x6)
 object WasmI16 : WasmType("i16", -0x7)
 object WasmFuncRef : WasmType("funcref", -0x10)
-object WasmAnyRef : WasmType("anyref", -0x11)
+object WasmExternRef : WasmType("externref", -0x11)
+object WasmAnyRef : WasmType("anyref", -0x12)
 object WasmEqRef : WasmType("eqref", -0x13)
 
 data class WasmRefNullType(val heapType: WasmHeapType) : WasmType("ref null", -0x14)
@@ -44,7 +45,8 @@ sealed class WasmHeapType {
 
     sealed class Simple(val name: String, val code: Byte) : WasmHeapType() {
         object Func : Simple("func", -0x10)
-        object Any : Simple("any", -0x11)
+        object Extern : Simple("extern", -0x11)
+        object Any : Simple("any", -0x12)
         object Eq : Simple("eq", -0x13)
 
         @Suppress("unused")
@@ -71,5 +73,6 @@ fun WasmType.getHeapType(): WasmHeapType =
         is WasmEqRef -> WasmHeapType.Simple.Eq
         is WasmAnyRef -> WasmHeapType.Simple.Any
         is WasmFuncRef -> WasmHeapType.Simple.Func
+        is WasmExternRef -> WasmHeapType.Simple.Extern
         else -> error("Unknown heap type for type $this")
     }

wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/convertors/WasmBinaryToIR.kt

@@ -468,6 +468,7 @@ class WasmBinaryToIR(val b: MyByteReader) {
         WasmI16,
         WasmFuncRef,
         WasmAnyRef,
+        WasmExternRef,
         WasmEqRef
     ).associateBy { it.code }
 
@@ -490,7 +491,7 @@ class WasmBinaryToIR(val b: MyByteReader) {
 
         return when (code.toInt()) {
             0x70 -> WasmFuncRef
-            0x6F -> WasmAnyRef
+            0x6F -> WasmExternRef
             else -> error("Unsupported heap type ${code.toString(16)}")
         }
     }

wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/convertors/WasmIrToText.kt

@@ -453,6 +453,7 @@ class WasmIrToText : SExpressionBuilder() {
         when (type) {
             is WasmFuncRef -> appendElement("func")
             is WasmAnyRef -> appendElement("any")
+            is WasmExternRef -> appendElement("extern")
             else -> TODO()
         }
     }