Fixed handling of text wrapping and a text layout corner case

Due to using QTextCursor::columnNumber() instead of
QTextCursor::positionInBlock(), a lot of code would not work correctly
when used with wrapped lines.

In addition, there was an issue with columnNumber() returning 0 right
after inserting a character before the last character of a line.

Reviewed-by: mae

src/plugins/qmljseditor/qmlexpressionundercursor.cpp

@@ -102,7 +102,7 @@ public:
         _cursor = cursor;
 
         QTextBlock block = _cursor.block();
-        const QString blockText = block.text().left(cursor.columnNumber());
+        const QString blockText = block.text().left(cursor.positionInBlock());
 
         scanner.setScanComments(false);
         const QList<Token> tokens = scanner(blockText, startState(block));

src/plugins/qmljseditor/qmljscodecompletion.cpp

@@ -513,7 +513,7 @@ bool CodeCompletion::triggersCompletion(TextEditor::ITextEditable *editor)
 
             QTextCursor tc = ed->textCursor();
             QTextBlock block = tc.block();
-            const int column = tc.columnNumber();
+            const int column = tc.positionInBlock();
             const int blockState = qMax(0, block.previous().userState()) & 0xff;
             const QString blockText = block.text();
 

src/plugins/qmljseditor/qmljseditor.cpp

@@ -1130,7 +1130,7 @@ bool QmlJSTextEditor::contextAllowsAutoParentheses(const QTextCursor &cursor, co
 
     Scanner tokenize;
     const QList<Token> tokens = tokenize(blockText, blockState);
-    const int pos = cursor.columnNumber();
+    const int pos = cursor.positionInBlock();
 
     int tokenIndex = 0;
     for (; tokenIndex < tokens.size(); ++tokenIndex) {