[#2851] - Deadlock in "Image Expression" editor.

Deadlock in "Image Expression" editor.
It is NOT reproducible always. But from time to time it happens.

Following two threads are reason for it:
Name: ViewHierarchy-Region-Rebuilding
State: BLOCKED on org.netbeans.lib.lexer.inc.IncTokenList@794e1c owned by: EditorBracesMatching
Total blocked: 261 Total waited: 154

Stack trace:
org.netbeans.lib.lexer.TokenHierarchyOperation.tokenSequence(TokenHierarchyOperation.java:411)
org.netbeans.lib.lexer.TokenHierarchyOperation.tokenSequence(TokenHierarchyOperation.java:405)
org.netbeans.api.lexer.TokenHierarchy.tokenSequence(TokenHierarchy.java:186)
org.netbeans.modules.languages.features.LanguagesHighlightsLayer.getHighlights(LanguagesHighlightsLayer.java:70)
org.netbeans.modules.editor.lib2.highlighting.ProxyHighlightsContainer.getHighlights(ProxyHighlightsContainer.java:131)
- locked java.lang.String@bf3474
org.netbeans.modules.editor.lib2.view.HighlightsViewFactory.updateHighlight(HighlightsViewFactory.java:179)
org.netbeans.modules.editor.lib2.view.HighlightsViewFactory.createView(HighlightsViewFactory.java:124)
org.netbeans.modules.editor.lib2.view.ViewBuilder.createNextView(ViewBuilder.java:473)
org.netbeans.modules.editor.lib2.view.ViewBuilder.createViews(ViewBuilder.java:412)
org.netbeans.modules.editor.lib2.view.ViewBuilder.createReplaceAndRepaintViews(ViewBuilder.java:705)
org.netbeans.modules.editor.lib2.view.ViewUpdates.syncedViewsRebuild(ViewUpdates.java:397)
org.netbeans.modules.editor.lib2.view.DocumentView$2.run(DocumentView.java:397)
org.netbeans.modules.editor.lib2.view.DocumentView.runTransaction(DocumentView.java:370)
org.netbeans.modules.editor.lib2.view.DocumentView$1.run(DocumentView.java:383)
org.netbeans.editor.BaseDocument.render(BaseDocument.java:1422)
org.netbeans.modules.editor.lib2.view.DocumentView.runReadLockTransaction(DocumentView.java:380)
org.netbeans.modules.editor.lib2.view.DocumentView.syncViewsRebuild(DocumentView.java:393)
org.netbeans.modules.editor.lib2.view.ViewUpdates$RebuildViews.run(ViewUpdates.java:464)
org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)

Name: EditorBracesMatching
State: BLOCKED on java.lang.String@bf3474 owned by: ViewHierarchy-Region-Rebuilding
Total blocked: 11 Total waited: 8

Stack trace:
org.netbeans.modules.editor.lib2.highlighting.ProxyHighlightsContainer.layerChanged(ProxyHighlightsContainer.java:222)
org.netbeans.modules.editor.lib2.highlighting.ProxyHighlightsContainer.access$200(ProxyHighlightsContainer.java:66)
org.netbeans.modules.editor.lib2.highlighting.ProxyHighlightsContainer$LayerListener.highlightChanged(ProxyHighlightsContainer.java:256)
org.netbeans.spi.editor.highlighting.support.AbstractHighlightsContainer.fireHighlightsChange(AbstractHighlightsContainer.java:113)
org.netbeans.modules.editor.lib2.highlighting.SyntaxHighlighting.tokenHierarchyChanged(SyntaxHighlighting.java:151)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:459)
$Proxy55.tokenHierarchyChanged(Unknown Source)
org.netbeans.lib.lexer.TokenHierarchyOperation.fireTokenHierarchyChanged(TokenHierarchyOperation.java:521)
org.netbeans.lib.lexer.TokenHierarchyOperation.setActiveImpl(TokenHierarchyOperation.java:332)
org.netbeans.lib.lexer.TokenHierarchyOperation.isActiveImpl(TokenHierarchyOperation.java:359)
org.netbeans.lib.lexer.TokenHierarchyOperation.isActive(TokenHierarchyOperation.java:352)
- locked org.netbeans.lib.lexer.inc.IncTokenList@794e1c
org.netbeans.api.lexer.TokenHierarchy.isActive(TokenHierarchy.java:356)
org.netbeans.modules.editor.bracesmatching.MasterMatcher$1.run(MasterMatcher.java:420)
org.netbeans.editor.BaseDocument.render(BaseDocument.java:1422)
org.netbeans.modules.editor.bracesmatching.MasterMatcher.findFactories(MasterMatcher.java:417)
org.netbeans.modules.editor.bracesmatching.MasterMatcher.access$1200(MasterMatcher.java:66)
org.netbeans.modules.editor.bracesmatching.MasterMatcher$Result.findOrigin(MasterMatcher.java:709)
org.netbeans.modules.editor.bracesmatching.MasterMatcher$Result._run(MasterMatcher.java:578)
org.netbeans.modules.editor.bracesmatching.MasterMatcher$Result.run(MasterMatcher.java:533)
org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)