Remove support for EXPERIMENTAL_JAVA_LANGUAGE_LEVEL_9.

Prior to this change, setting that to "false" turned the default Java
language level back to 8. This change removes that option.

Bug: 115604102
Test: m java droid docs tests cts
Change-Id: I97bfd0dc8d941008b4071c6efe1c0c24950c4f1f
diff --git a/java/droiddoc.go b/java/droiddoc.go
index 12335ff..1091331 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -425,16 +425,12 @@
 		if sdkDep.hasStandardLibs() {
 			if sdkDep.useDefaultLibs {
 				ctx.AddVariationDependencies(nil, bootClasspathTag, config.DefaultBootclasspathLibraries...)
-				if ctx.Config().TargetOpenJDK9() {
-					ctx.AddVariationDependencies(nil, systemModulesTag, config.DefaultSystemModules)
-				}
+				ctx.AddVariationDependencies(nil, systemModulesTag, config.DefaultSystemModules)
 				if sdkDep.hasFrameworkLibs() {
 					ctx.AddVariationDependencies(nil, libTag, config.DefaultLibraries...)
 				}
 			} else if sdkDep.useModule {
-				if ctx.Config().TargetOpenJDK9() {
-					ctx.AddVariationDependencies(nil, systemModulesTag, sdkDep.systemModules)
-				}
+				ctx.AddVariationDependencies(nil, systemModulesTag, sdkDep.systemModules)
 				ctx.AddVariationDependencies(nil, bootClasspathTag, sdkDep.modules...)
 			}
 		} else if sdkDep.systemModules != "" {