K2JSCompilerArguments: sourceMapEmbedSources should be null by default.

When sourceMapEmbedSources are not null and source maps is disabled warning is reported, since it has effect only when source maps are enabled. Also this fixes some JPS JS with warnings count assertions.

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JSCompilerArguments.kt

@@ -55,13 +55,17 @@ class K2JSCompilerArguments : CommonCompilerArguments() {
     )
     var sourceMapBaseDirs: String? by NullableStringFreezableVar(null)
 
+    /**
+     * SourceMapEmbedSources should be null by default, since it has effect only when source maps are enabled.
+     * When sourceMapEmbedSources are not null and source maps is disabled warning is reported.
+     */
     @GradleOption(DefaultValues.JsSourceMapContentModes::class)
     @Argument(
             value = "-source-map-embed-sources",
             valueDescription = "{ always, never, inlining }",
             description = "Embed source files into source map"
     )
-    var sourceMapEmbedSources: String? by NullableStringFreezableVar(K2JsArgumentConstants.SOURCE_MAP_SOURCE_CONTENT_INLINING)
+    var sourceMapEmbedSources: String? by NullableStringFreezableVar(null)
 
     @GradleOption(DefaultValues.BooleanTrueDefault::class)
     @Argument(value = "-meta-info", description = "Generate .meta.js and .kjsm files with metadata. Use to create a library")