Remove unused private fields.

Fixes compilation when -Wunused-private-field is enabled (e.g., when
using -Wall).

src/google/protobuf/compiler/java/java_map_field.cc

@@ -156,9 +156,7 @@ ImmutableMapFieldGenerator(const FieldDescriptor* descriptor,
                                        int messageBitIndex,
                                        int builderBitIndex,
                                        Context* context)
-  : descriptor_(descriptor), messageBitIndex_(messageBitIndex),
-    builderBitIndex_(builderBitIndex), context_(context),
-    name_resolver_(context->GetNameResolver())  {
+  : descriptor_(descriptor), name_resolver_(context->GetNameResolver())  {
   SetMessageVariables(descriptor, messageBitIndex, builderBitIndex,
                       context->GetFieldGeneratorInfo(descriptor),
                       name_resolver_, &variables_);

src/google/protobuf/compiler/java/java_map_field.h

@@ -68,9 +68,6 @@ class ImmutableMapFieldGenerator : public ImmutableFieldGenerator {
  private:
   const FieldDescriptor* descriptor_;
   map<string, string> variables_;
-  const int messageBitIndex_;
-  const int builderBitIndex_;
-  Context* context_;
   ClassNameResolver* name_resolver_;
 };
 

src/google/protobuf/compiler/java/java_map_field_lite.cc

@@ -139,9 +139,7 @@ ImmutableMapFieldLiteGenerator(const FieldDescriptor* descriptor,
                                        int messageBitIndex,
                                        int builderBitIndex,
                                        Context* context)
-  : descriptor_(descriptor), messageBitIndex_(messageBitIndex),
-    builderBitIndex_(builderBitIndex), context_(context),
-    name_resolver_(context->GetNameResolver())  {
+  : descriptor_(descriptor), name_resolver_(context->GetNameResolver())  {
   SetMessageVariables(descriptor, messageBitIndex, builderBitIndex,
                       context->GetFieldGeneratorInfo(descriptor),
                       name_resolver_, &variables_);

src/google/protobuf/compiler/java/java_map_field_lite.h

@@ -67,9 +67,6 @@ class ImmutableMapFieldLiteGenerator : public ImmutableFieldLiteGenerator {
  private:
   const FieldDescriptor* descriptor_;
   map<string, string> variables_;
-  const int messageBitIndex_;
-  const int builderBitIndex_;
-  Context* context_;
   ClassNameResolver* name_resolver_;
 };