CppTools: Do not wait in GUI thread for the parsed document

...when collecting data for the semantic highlighting recalculation.

Task-number: QTCREATORBUG-11037

Change-Id: Ibed73a2916df0a91aedef166de2c8c6bb5df309c
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
CppTools: Remove invalid optimization for highlighting

The optimization in question could lead to an empty source and thus to
no highlighting. Checking for 'force' and the revisions is at this point
not enough since later the semantic info calculcation can be aborted, so
that a subsequent recalculation would get an empty document.

contents() itself is already optimized (uses caching).

Task-number: QTCREATORBUG-11367
Change-Id: If31a8ab0c848e4babd38104961fb9812f077a2be
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
CppTools: Fix data race when accessing the editor revision

Addresses the following findings of QTCREATORBUG-12030:
 * qtc.helgrind.plugintests.txt#2
 * qtc.helgrind.usingEditors1.txt#1

Helgrind report (truncated):

Possible data race during write of size 4 at 0x23679618 by thread #1
Locks held: none
   at 0x6819003: ???
   by 0x681D713: ???
   by 0x68200DE: ???
   by 0x684B8F8: QTextCursor::insertText(QString const&, QTextCharFormat const&)
   by 0x684BCB9: QTextCursor::insertText(QString const&)
   by 0x139DA06C: TextEditor::BaseTextEditorWidget::keyPressEvent(QKeyEvent*) (basetexteditor.cpp:1866)
   by 0x184C999F: CppEditor::Internal::CPPEditorWidget::keyPressEvent(QKeyEvent*) (cppeditor.cpp:1416)

This conflicts with a previous read of size 4 by thread #18
Locks held: none
   at 0x680BC54: QTextDocument::revision() const
   by 0x159047F3: CppTools::CppEditorSupport::editorRevision() const (cpptoolseditorsupport.cpp:198)
   by 0x158E39BF: CppTools::Internal::CppModelManager::buildWorkingCopyList() (cppmodelmanager.cpp:525)
   by 0x158E3D5B: CppTools::Internal::CppModelManager::workingCopy() const (cppmodelmanager.cpp:544)
   by 0x1589FF6F: CppTools::Internal::CppCompletionAssistInterface::getCppSpecifics() const (cppcompletionassist.cpp:1957)
   by 0x158A1158: CppTools::Internal::CppCompletionAssistInterface::snapshot() const (cppcompletionassist.h:200)
   by 0x1589707C: CppTools::Internal::CppCompletionAssistProcessor::startCompletionInternal(QString, unsigned int, unsigned int, QString const&, int) (cppcompletionassist.cpp:1212)
   by 0x15893CC7: CppTools::Internal::CppCompletionAssistProcessor::startCompletionHelper() (cppcompletionassist.cpp:970)

---

Possible data race during write of size 4 at 0x24C8AD18 by thread #1
Locks held: none
   at 0x684AF23: QTextCursor::beginEditBlock()
   by 0x139D7D05: TextEditor::BaseTextEditorWidget::keyPressEvent(QKeyEvent*) (basetexteditor.cpp:1578)
   by 0x184C999F: CppEditor::Internal::CPPEditorWidget::keyPressEvent(QKeyEvent*) (cppeditor.cpp:1416)
   ...
   by 0x40F15A: main (main.cpp:533)

This conflicts with a previous read of size 4 by thread #11
Locks held: none
   at 0x680BC54: QTextDocument::revision() const
   by 0x159048D3: CppTools::CppEditorSupport::editorRevision() const (cpptoolseditorsupport.cpp:198)
   by 0x158E3A9F: CppTools::Internal::CppModelManager::buildWorkingCopyList() (cppmodelmanager.cpp:525)
   by 0x158E3E3B: CppTools::Internal::CppModelManager::workingCopy() const (cppmodelmanager.cpp:544)
   by 0x1590741E: parse(QFutureInterface<void>&, QSharedPointer<CppTools::SnapshotUpdater>) (cpptoolseditorsupport.cpp:299)

Task-number: QTCREATORBUG-12030
Change-Id: Idf0aa47f1f6bfd6814a961fe39d3b19b98f934f5
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>