I saw this table in this section:
In the third column from the bottom, it says "Proposed cancel":
In the United Sates when big projects are slipping and way over budget, there are points in the process where the government has to decide if the project should continue. In 2011 JWST reached one of those decision points.
So at a point in the budget process a proposal was made to cancel the project. The project survived the effort to cancel it. The Wikipedia article you linked to mentions this:
On 6 July 2011, the United States House of Representatives' appropriations committee on Commerce, Justice, and Science moved to cancel the James Webb project by proposing an FY2012 budget that removed 1.9 billion from NASA's overall budget, of which roughly one quarter was for JWST. 3 billion had been spent and 75% of its hardware was in production. This budget proposal was approved by subcommittee vote the following day. The committee charged that the project was "billions of dollars over budget and plagued by poor management". In response, the American Astronomical Society issued a statement in support of JWST, as did Senator Mikulski. A number of editorials supporting JWST appeared in the international press during 2011 as well. In November 2011, Congress reversed plans to cancel JWST and instead capped additional funding to complete the project at US$8 billion.