Fix toString('base64') bug

Thanks to Stepan Stolyarov for the test case.

src/node_buffer.cc

@@ -327,7 +327,7 @@ Handle<Value> Buffer::Base64Slice(const Arguments &args) {
   int out_len = (n + 2 - ((n + 2) % 3)) / 3 * 4;
   char *out = new char[out_len];
 
-  char bitbuf[3];
+  uint8_t bitbuf[3];
   int i = start; // data() index
   int j = 0; // out index
   char c;

test/simple/test-buffer.js

@@ -306,3 +306,11 @@ assert.equal(new Buffer('72INjkR5fchcxk9+VgdGPFJDxUBFR5/rMFsghgxADiw',   'base64
 assert.equal(new Buffer('w69jACy6BgZmaFvv96HG6MYksWytuZu3T1FvGnulPg==',  'base64').length, 31);
 assert.equal(new Buffer('w69jACy6BgZmaFvv96HG6MYksWytuZu3T1FvGnulPg=',   'base64').length, 31);
 assert.equal(new Buffer('w69jACy6BgZmaFvv96HG6MYksWytuZu3T1FvGnulPg',    'base64').length, 31);
+
+// This string encodes single '.' character in UTF-16
+dot = new Buffer('//4uAA==', 'base64');
+assert.equal(dot[0], 0xff);
+assert.equal(dot[1], 0xfe);
+assert.equal(dot[2], 0x2e);
+assert.equal(dot[3], 0x00);
+assert.equal(dot.toString('base64'), '//4uAA==');