Rename SuccessOrFailure to Result and hide Failure from ABI

* The members of Result are isSuccess, isFailure, exceptionOrNull, getOrNull
* The rest of API is implemented via inline-only extensions
* There are two internal functions to hide detailed mechanics of an internal
  Result.Failure class: createFailure and throwOnFailure
* Result.toString is explicit: either Success(v) or Failure(x)

See KT-26538

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineCodegen.kt

@@ -64,7 +64,7 @@ abstract class AbstractCoroutineCodegen(
         if (languageVersionSettings.isReleaseCoroutines())
             createImplMethod(
                 INVOKE_SUSPEND_METHOD_NAME,
-                "result" to classDescriptor.module.getSuccessOrFailure(classDescriptor.builtIns.anyType)
+                "result" to classDescriptor.module.getResult(classDescriptor.builtIns.anyType)
             )
         else
             createImplMethod(

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineTransformerMethodVisitor.kt

@@ -759,11 +759,11 @@ private fun InstructionAdapter.generateResumeWithExceptionCheck(isReleaseCorouti
     val noExceptionLabel = Label()
 
     if (isReleaseCoroutines) {
-        instanceOf(AsmTypes.SUCCESS_OR_FAILURE_FAILURE)
+        instanceOf(AsmTypes.RESULT_FAILURE)
         ifeq(noExceptionLabel)
         // TODO: do we need this checkcast?
-        checkcast(AsmTypes.SUCCESS_OR_FAILURE_FAILURE)
-        getfield(AsmTypes.SUCCESS_OR_FAILURE_FAILURE.internalName, "exception", AsmTypes.JAVA_THROWABLE_TYPE.descriptor)
+        checkcast(AsmTypes.RESULT_FAILURE)
+        getfield(AsmTypes.RESULT_FAILURE.internalName, "exception", AsmTypes.JAVA_THROWABLE_TYPE.descriptor)
     } else {
         ifnull(noExceptionLabel)
     }

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/coroutineCodegenUtil.kt

@@ -303,16 +303,16 @@ fun <D : FunctionDescriptor> D.createCustomCopy(
 private fun FunctionDescriptor.getContinuationParameterTypeOfSuspendFunction(isReleaseCoroutines: Boolean) =
     module.getContinuationOfTypeOrAny(returnType!!, if (this.needsExperimentalCoroutinesWrapper()) false else isReleaseCoroutines)
 
-fun ModuleDescriptor.getSuccessOrFailure(kotlinType: KotlinType) =
+fun ModuleDescriptor.getResult(kotlinType: KotlinType) =
     module.resolveTopLevelClass(
-        DescriptorUtils.SUCCESS_OR_FAILURE_FQ_NAME,
+        DescriptorUtils.RESULT_FQ_NAME,
         NoLookupLocation.FROM_BACKEND
     )?.defaultType?.let {
         KotlinTypeFactory.simpleType(
             it,
             arguments = listOf(kotlinType.asTypeProjection())
         )
-    } ?: ErrorUtils.createErrorType("For SuccessOrFailure")
+    } ?: ErrorUtils.createErrorType("For Result")
 
 private fun MethodNode.invokeNormalizeContinuation(languageVersionSettings: LanguageVersionSettings) {
     visitMethodInsn(

compiler/backend/src/org/jetbrains/kotlin/codegen/state/inlineClassManglingUtils.kt

@@ -8,7 +8,6 @@ package org.jetbrains.kotlin.codegen.state
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.load.kotlin.getRepresentativeUpperBound
 import org.jetbrains.kotlin.resolve.DescriptorUtils.RESULT_FQ_NAME
-import org.jetbrains.kotlin.resolve.DescriptorUtils.SUCCESS_OR_FAILURE_FQ_NAME
 import org.jetbrains.kotlin.resolve.InlineClassDescriptorResolver
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameUnsafe
@@ -50,7 +49,7 @@ private fun KotlinType.isInlineClassThatRequiresMangling() =
     isInlineClassType() && !isDontMangleClass(this.constructor.declarationDescriptor as ClassDescriptor)
 
 private fun isDontMangleClass(classDescriptor: ClassDescriptor) =
-    classDescriptor.fqNameSafe == SUCCESS_OR_FAILURE_FQ_NAME || classDescriptor.fqNameSafe == RESULT_FQ_NAME
+    classDescriptor.fqNameSafe == RESULT_FQ_NAME
 
 private fun KotlinType.isTypeParameterWithUpperBoundThatRequiresMangling(): Boolean {
     val descriptor = constructor.declarationDescriptor as? TypeParameterDescriptor ?: return false