16 files declare their use of ProcessBuilder

BaseCompressorFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/Yui/BaseCompressorFilter.php
CoffeeScriptFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/CoffeeScriptFilter.php
CompassFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/CompassFilter.php
CompilerJarFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/GoogleClosure/CompilerJarFilter.php
CssEmbedFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/CssEmbedFilter.php
GssFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/GssFilter.php
JpegoptimFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/JpegoptimFilter.php
JpegtranFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/JpegtranFilter.php
LessFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/LessFilter.php
OptiPngFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/OptiPngFilter.php
PngoutFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/PngoutFilter.php
ProcessBuilderTest.php in drupal/core/vendor/symfony/process/Symfony/Component/Process/Tests/ProcessBuilderTest.php
SassFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/Sass/SassFilter.php
SprocketsFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/SprocketsFilter.php
StylusFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/StylusFilter.php
UglifyJsFilter.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Filter/UglifyJsFilter.php