Debugger: Allow watching complex expression for QML

Latest restructuring made the 'Add Expression Evaluator'
action to a no-op when not debugging.
Reflect this by disabling the action as long the user is
not debugging and allow complex expressions to be evaluated
for QML as well.

Fixes: QTCREATORBUG-19050
Change-Id: I2d6421a121e2169981b992a617f4d2b7264a8091
Reviewed-by: hjk <hjk@qt.io>

src/plugins/debugger/debuggerplugin.cpp

@@ -1629,7 +1629,7 @@ void DebuggerPluginPrivate::updatePresetState()
     m_attachToRunningApplication.setEnabled(true);
     m_attachToUnstartedApplication.setEnabled(true);
 
-    m_watchAction.setEnabled(true);
+    m_watchAction.setEnabled(state != DebuggerFinished && state != DebuggerNotReady);
     m_breakAction.setEnabled(true);
 }
 
@@ -2055,7 +2055,7 @@ void DebuggerPluginPrivate::setInitialState()
     m_attachToUnstartedApplication.setEnabled(true);
     m_detachAction.setEnabled(false);
 
-    m_watchAction.setEnabled(true);
+    m_watchAction.setEnabled(false);
     m_breakAction.setEnabled(false);
     //m_snapshotAction.setEnabled(false);
     action(OperateByInstruction)->setChecked(false);

src/plugins/debugger/qml/qmlengine.cpp

@@ -962,7 +962,8 @@ bool QmlEngine::hasCapability(unsigned cap) const
 {
     return cap & (AddWatcherCapability
             | AddWatcherWhileRunningCapability
-            | RunToLineCapability);
+            | RunToLineCapability
+            | WatchComplexExpressionsCapability);
     /*ReverseSteppingCapability | SnapshotCapability
         | AutoDerefPointersCapability | DisassemblerCapability
         | RegisterCapability | ShowMemoryCapability