Qt assertion failure crash opening Preferences on OSX 10.10 Yosemite

The version of the QT framework in use by Musescore nightly builds and v2 beta crashes consistently when opening the preferences windows on Mac OSX 10.10 Yosemite (any of the betas/DPs). This occurs whether the preferences have been reset or not.

The exact issue is a failed assert within the Qt framework (so not Musescore's fault directly). This bug has been fixed in versions of Qt >= 5.3.1 -- see QTBUG-39504.

The only fix that should be required to solve this is to update to Qt framework v5.3.1 or higher.

Application Specific Information:
Assertion failed: (_consumed <= scratch_size), function _hb_coretext_shape, file src/hb-coretext.cc, line 764.
 
Performing @selector(itemFired:) from sender NSMenuItem 0x6000000bb300

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib        	0x00007fff94567282 __pthread_kill + 10
1   libsystem_c.dylib             	0x00007fff8ac015d3 abort + 129
2   libsystem_c.dylib             	0x00007fff8abc96b9 __assert_rtn + 321
3   QtGui                         	0x000000010bc8b664 0x10b94d000 + 3401316
4   QtGui                         	0x000000010bc6732c 0x10b94d000 + 3253036
5   QtGui                         	0x000000010bc66b02 0x10b94d000 + 3250946
6   QtGui                         	0x000000010ba27d93 QTextEngine::shapeTextWithHarfbuzzNG(QScriptItem const&, unsigned short const*, int, QFontEngine*, QVector const&, bool) const + 531
7   QtGui                         	0x000000010ba27057 QTextEngine::shapeText(int) const + 2439
8   QtGui                         	0x000000010ba26484 QTextEngine::shape(int) const + 420
9   QtGui                         	0x000000010ba3bcb9 QTextLine::layout_helper(int) + 2265
10  QtGui                         	0x000000010ba3b38d QTextLine::setLineWidth(double) + 237
11  QtWidgets                     	0x000000010d006d02 0x10cf6f000 + 621826
12  QtWidgets                     	0x000000010d006c26 0x10cf6f000 + 621606
13  QtWidgets                     	0x000000010d007518 0x10cf6f000 + 623896
14  QtWidgets                     	0x000000010d0181db QCommonStyle::sizeFromContents(QStyle::ContentsType, QStyleOption const*, QSize const&, QWidget const*) const + 1387
15  org.musescore.MuseScore       	0x000000010a5cf6d7 MgStyle::sizeFromContents(QStyle::ContentsType, QStyleOption const*, QSize const&, QWidget const*) const + 103