commented out dojo.provide would break optimize

[liucougar]

if a file has the following code:

//dojo.provide("dojox.xml.DomParser");

it will be converted to:

///* builder delete begin
dojo.provide("dojox.xml.DomParser");


 builder delete end */

this will trigger invalid syntax error, something like this:

line 3974: missing ; before statement
js:  builder delete end */
js: ...............^

and the build would fail with:

net.js:391
    throw new Error('Socket is not writable');
          ^
Error: Socket is not writable
    at Socket._writeOut (net.js:391:11)
    at Socket.write (net.js:377:17)
    at Object.write (build/transforms/writeOptimized:169:21)
    at build/transforms/writeOptimized:122:29
    at build/transforms/writeOptimized:265:5
    at Array.0 (build/transforms/writeOptimized:273:11)
    at build/main:127:23
    at build/main:106:5
    at build/transforms/writeAmd:171:5
    at build/node/fs:23:9

[liucougar]

in order to track this bug down, I had to modify the function which listens on runner.stderr data in build/transforms/writeOptimized.js

i'd suggest a way of outputing stderr from the sub-process (and also print out what file the sub-process was processing when the error was reported) to give user more hints on what's causing the issue

[Rawld Gill]

Conversion of legacy modules was reworked in [25768], and this defect was fixed at that time.