Do not write version requirements for InlineClasses

Language feature InlineClasses is enabled since 1.3. The current lowest
supported language version is 1.4, so any compiler that can read
binaries produced by the current compiler also supports inline classes,
which means that the version requirement is not needed anymore.

No issue reported because it's mostly not a user-visible change. The
main effect is that it reduces differences in metadata between K1 and
K2, because K2 never supported writing this version requirement properly
due to the TODO in `hasInlineClassTypesInSignature`.

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt

@@ -277,8 +277,6 @@ class FirElementSerializer private constructor(
 
         extension.serializeClass(klass, builder, versionRequirementTable, this)
 
-        writeVersionRequirementForInlineClasses(klass, builder, versionRequirementTable)
-
         if (metDefinitelyNotNullType) {
             builder.addVersionRequirement(
                 writeLanguageVersionRequirement(LanguageFeature.DefinitelyNonNullableTypes, versionRequirementTable)
@@ -484,10 +482,6 @@ class FirElementSerializer private constructor(
                 builder.addVersionRequirement(writeVersionRequirementDependingOnCoroutinesVersion())
             }
 
-            if (property.hasInlineClassTypesInSignature()) {
-                builder.addVersionRequirement(writeVersionRequirement(LanguageFeature.InlineClasses))
-            }
-
             if (local.metDefinitelyNotNullType) {
                 builder.addVersionRequirement(writeVersionRequirement(LanguageFeature.DefinitelyNonNullableTypes))
             }
@@ -583,10 +577,6 @@ class FirElementSerializer private constructor(
                 builder.addVersionRequirement(writeVersionRequirementDependingOnCoroutinesVersion())
             }
 
-            if (function.hasInlineClassTypesInSignature()) {
-                builder.addVersionRequirement(writeVersionRequirement(LanguageFeature.InlineClasses))
-            }
-
             if (local.metDefinitelyNotNullType) {
                 builder.addVersionRequirement(writeVersionRequirement(LanguageFeature.DefinitelyNonNullableTypes))
             }
@@ -693,10 +683,6 @@ class FirElementSerializer private constructor(
                 builder.addVersionRequirement(writeVersionRequirementDependingOnCoroutinesVersion())
             }
 
-            if (constructor.hasInlineClassTypesInSignature()) {
-                builder.addVersionRequirement(writeVersionRequirement(LanguageFeature.InlineClasses))
-            }
-
             if (local.metDefinitelyNotNullType) {
                 builder.addVersionRequirement(writeVersionRequirement(LanguageFeature.DefinitelyNonNullableTypes))
             }
@@ -1076,28 +1062,11 @@ class FirElementSerializer private constructor(
 
     private fun useTypeTable(): Boolean = extension.shouldUseTypeTable()
 
-    private fun FirDeclaration.hasInlineClassTypesInSignature(): Boolean {
-        // TODO
-        return false
-    }
-
     private fun FirCallableDeclaration.isSuspendOrHasSuspendTypesInSignature(): Boolean {
         // TODO (types in signature)
         return this.isSuspend
     }
 
-    private fun writeVersionRequirementForInlineClasses(
-        klass: FirClass,
-        builder: ProtoBuf.Class.Builder,
-        versionRequirementTable: MutableVersionRequirementTable
-    ) {
-        if (klass !is FirRegularClass || !klass.isInline && !klass.hasInlineClassTypesInSignature()) return
-
-        builder.addVersionRequirement(
-            writeLanguageVersionRequirement(LanguageFeature.InlineClasses, versionRequirementTable)
-        )
-    }
-
     private fun MutableVersionRequirementTable.serializeVersionRequirements(container: FirAnnotationContainer): List<Int> =
         serializeVersionRequirements(container.annotations)