Fixed javac environment's Java8 resolve() method, implemented Java9 v…

…ersion.

	Change on 2016/11/21 by tball <tball@google.com>

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=139816214

translator/src/main/java/com/google/devtools/j2objc/javac/JavacEnvironment.java

@@ -23,6 +23,7 @@
 import com.sun.tools.javac.util.Context;
 import com.sun.tools.javac.util.Name;
 import com.sun.tools.javac.util.Names;
+import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import javax.lang.model.element.Element;
@@ -70,18 +71,27 @@ public Element resolve(String name) {
 
   private ClassSymbol enterClassJavac(Name className) {
     try {
-      Method m = ClassReader.class.getDeclaredMethod("enterName", Name.class);
+      Method m = ClassReader.class.getDeclaredMethod("enterClass", Name.class);
       return (ClassSymbol) m.invoke(classReader, className);
     } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
       return null;
     }
   }
 
   private ClassSymbol enterClassJavac9(Name className) {
+    // TODO(tball): remove reflection use when Java 9 is minimum version.
     try {
-      Method m = Symtab.class.getDeclaredMethod("enterName", Name.class);
-      return (ClassSymbol) m.invoke(symbolTable, className);
-    } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
+      Field javaBaseField = Names.class.getDeclaredField("java_base");
+      Name javaBaseName = (Name) javaBaseField.get(javacNames);
+
+      Class<?> moduleSymbolCls = Class.forName("com.sun.tools.javac.code.Symbol.MethodSymbol");
+      Method enterModule = Symtab.class.getDeclaredMethod("enterModule", Name.class);
+      Object javaBaseModule = enterModule.invoke(symbolTable, javaBaseName);
+
+      Method enterClass = Symtab.class.getDeclaredMethod("enterClass", moduleSymbolCls, Name.class);
+      return (ClassSymbol) enterClass.invoke(symbolTable, javaBaseModule, className);
+    } catch (ClassNotFoundException | NoSuchFieldException | NoSuchMethodException
+        | InvocationTargetException | IllegalAccessException e) {
       return null;
     }
   }