[Platform API] Introduce fundamental abstraction of Platform

This is a large commit, which introduces general API for working with
abstraction of Platform.

- Add new abstraction to 'core' - SimplePlatform - which represents
exactly one platform
  - Clients are strongly prohibited to create instances of SimplePlatform
  by hand, instead, corresponding *Platforms abstraction should be used
  (e.g. JvmPlatforms, JsPlatforms, KonanPlatforms)

- Move TargetPlatform to 'core', it represents now a collection of
SimplePlatforms
  - Clients are strongly encouraged to use TargetPlatform
    (not SimplePlatform) in API, to enforce checks for multiplatform

- Provide a helper-extensions to work with TargetPlatform
(in particular, for getting a specific component platform)

- Remove MultiTargetPlatform in favour of TargetPlatform
  - Notably, this commit leaves another widely used duplicated abstraction,
    namely, IdePlatform. For the sake sanity, removal of IdePlatform is
    extracted in the separate commit.

js/js.frontend/src/org/jetbrains/kotlin/frontend/js/di/injection.kt

@@ -17,7 +17,6 @@
 package org.jetbrains.kotlin.frontend.js.di
 
 import org.jetbrains.kotlin.config.LanguageVersionSettings
-import org.jetbrains.kotlin.config.TargetPlatformVersion
 import org.jetbrains.kotlin.container.get
 import org.jetbrains.kotlin.container.useImpl
 import org.jetbrains.kotlin.container.useInstance
@@ -28,7 +27,6 @@ import org.jetbrains.kotlin.descriptors.impl.ModuleDescriptorImpl
 import org.jetbrains.kotlin.frontend.di.configureModule
 import org.jetbrains.kotlin.incremental.components.ExpectActualTracker
 import org.jetbrains.kotlin.incremental.components.LookupTracker
-import org.jetbrains.kotlin.js.resolve.JsPlatform
 import org.jetbrains.kotlin.js.resolve.JsPlatformCompilerServices
 import org.jetbrains.kotlin.resolve.*
 import org.jetbrains.kotlin.resolve.lazy.KotlinCodeAnalyzer
@@ -46,7 +44,12 @@ fun createTopDownAnalyzerForJs(
         additionalPackages: List<PackageFragmentProvider>
 ): LazyTopDownAnalyzer {
     val storageComponentContainer = createContainer("TopDownAnalyzerForJs", JsPlatformCompilerServices) {
-        configureModule(moduleContext, JsPlatform, TargetPlatformVersion.NoVersion, JsPlatformCompilerServices, bindingTrace)
+        configureModule(
+            moduleContext,
+            DefaultBuiltInPlatforms.jsPlatform,
+            JsPlatformCompilerServices,
+            bindingTrace
+        )
 
         useInstance(declarationProviderFactory)
         useImpl<AnnotationResolverImpl>()

js/js.frontend/src/org/jetbrains/kotlin/js/analyze/TopDownAnalyzerFacadeForJS.kt

@@ -67,7 +67,7 @@ object TopDownAnalyzerFacadeForJS {
             ProjectContext(project),
             Name.special("<$moduleName>"),
             builtIns,
-            multiTargetPlatform = null
+            platform = null
         )
 
         val additionalPackages = mutableListOf<PackageFragmentProvider>()

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/JsPlatform.kt

@@ -1,24 +0,0 @@
-/*
- * Copyright 2010-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.jetbrains.kotlin.js.resolve
-
-import org.jetbrains.kotlin.resolve.*
-
-object JsPlatform : TargetPlatform("JS") {
-    override val platform: MultiTargetPlatform
-        get() = MultiTargetPlatform.Specific(platformName)
-}

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/JsResolverForModuleFactory.kt

@@ -1,30 +1,20 @@
 /*
- * Copyright 2010-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.js.resolve
 
 import org.jetbrains.kotlin.analyzer.*
 import org.jetbrains.kotlin.config.LanguageVersionSettings
-import org.jetbrains.kotlin.config.TargetPlatformVersion
 import org.jetbrains.kotlin.container.get
 import org.jetbrains.kotlin.context.ModuleContext
 import org.jetbrains.kotlin.descriptors.impl.CompositePackageFragmentProvider
 import org.jetbrains.kotlin.descriptors.impl.ModuleDescriptorImpl
 import org.jetbrains.kotlin.frontend.di.createContainerForLazyResolve
 import org.jetbrains.kotlin.incremental.components.LookupTracker
+import org.jetbrains.kotlin.platform.TargetPlatform
+import org.jetbrains.kotlin.platform.js.JsPlatform
 import org.jetbrains.kotlin.resolve.BindingTraceContext
 import org.jetbrains.kotlin.resolve.TargetEnvironment
 import org.jetbrains.kotlin.resolve.lazy.ResolveSession
@@ -41,8 +31,7 @@ object JsResolverForModuleFactory : ResolverForModuleFactory() {
         platformParameters: PlatformAnalysisParameters,
         targetEnvironment: TargetEnvironment,
         resolverForProject: ResolverForProject<M>,
-        languageVersionSettings: LanguageVersionSettings,
-        targetPlatformVersion: TargetPlatformVersion
+        languageVersionSettings: LanguageVersionSettings
     ): ResolverForModule {
         val (moduleInfo, syntheticFiles, moduleContentScope) = moduleContent
         val project = moduleContext.project
@@ -58,8 +47,7 @@ object JsResolverForModuleFactory : ResolverForModuleFactory() {
             moduleContext,
             declarationProviderFactory,
             BindingTraceContext(/* allowSliceRewrite = */ true),
-            JsPlatform,
-            TargetPlatformVersion.NoVersion,
+            moduleDescriptor.platform!!,
             JsPlatformCompilerServices,
             targetEnvironment,
             languageVersionSettings

js/js.frontend/src/org/jetbrains/kotlin/platform/js/JsPlatform.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.platform.js
+
+import org.jetbrains.kotlin.platform.SimplePlatform
+import org.jetbrains.kotlin.platform.TargetPlatform
+import org.jetbrains.kotlin.platform.toTargetPlatform
+
+abstract class JsPlatform : SimplePlatform("JS") {
+    override val oldFashionedDescription: String
+        get() = "JavaScript "
+}
+
+object JsPlatforms {
+    val defaultJsPlatform: TargetPlatform = object : JsPlatform() {}.toTargetPlatform()
+
+    val allJsPlatforms: List<TargetPlatform> = listOf(defaultJsPlatform)
+}
+
+fun TargetPlatform?.isJs(): Boolean = this?.singleOrNull() is JsPlatform