Merge remote-tracking branch 'origin/5.5' into 5.6

Change-Id: Ibc7a47f7ce6d15dff79fdc59f8ded297d1b8d50d

diff --cc src/qml/jsapi/qjsvalue.cpp
Simple merge

diff --cc src/qml/qml/qqmlvaluetype.cpp
Simple merge

diff --cc src/quick/items/context2d/qquickcontext2d.cpp
Simple merge

diff --cc tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp
Simple merge

diff --cc tools/qmlplugindump/main.cpp
Simple merge