pull request to fix the issue #3845

[zhuzisheng]

What this PR does / why we need it:
this pr fix the error when using +'gg' and the number is larger than the document line.
Which issue(s) this PR fixes
#3845

Special notes for your reviewer:

[TravisBuddy]

Travis tests have failed

Hey @zhuzisheng,
Please read the following log in order to understand the failure reason.
It'll be awesome if you fix what's wrong and commit the changes.

Node.js: 8

View build log

if [[ $(git diff-index HEAD -- *.js *.ts *.md) ]]; then git diff; echo "Prettier Failed. Run `gulp forceprettier` and commit changes to resolve."; exit 1; fi

The command "if [[ $(git diff-index HEAD -- *.js *.ts *.md) ]]; then git diff; echo "Prettier Failed. Run `gulp forceprettier` and commit changes to resolve."; exit 1; fi" exited with 0.

$ npm run build

> vim@1.8.1 build /home/travis/build/VSCodeVim/Vim
> gulp build

[02:41:35] Using gulpfile ~/build/VSCodeVim/Vim/gulpfile.js
[02:41:35] Starting 'build'...
[02:41:35] Starting 'prettier'...
[02:41:37] Finished 'prettier' after 2.22 s
[02:41:37] Starting 'tsc'...
[02:41:37] Starting 'tslint'...
[02:41:44] Finished 'tslint' after 7.58 s
### VS Code Extension Test Run ###

Current working directory: /home/travis/build/VSCodeVim/Vim
Downloading VS Code 1.35.1 into .vscode-test/vscode-1.35.1.
Downloading VS Code from: https://update.code.visualstudio.com/1.35.1/linux-x64/stable
Tests exited with code: 1
The command "npm test --silent" exited with 1.



Done. Your build exited with 1.

npm run build

> vim@1.8.1 build /home/travis/build/VSCodeVim/Vim
> gulp build

[02:41:35] Using gulpfile ~/build/VSCodeVim/Vim/gulpfile.js
[02:41:35] Starting 'build'...
[02:41:35] Starting 'prettier'...
[02:41:37] Finished 'prettier' after 2.22 s
[02:41:37] Starting 'tsc'...
[02:41:37] Starting 'tslint'...
[02:41:44] Finished 'tslint' after 7.58 s
### VS Code Extension Test Run ###

Current working directory: /home/travis/build/VSCodeVim/Vim
Downloading VS Code 1.35.1 into .vscode-test/vscode-1.35.1.
Downloading VS Code from: https://update.code.visualstudio.com/1.35.1/linux-x64/stable
Tests exited with code: 1
The command "npm test --silent" exited with 1.



Done. Your build exited with 1.

npm test --silent

Done. Your build exited with 1.

TravisBuddy Request Identifier: f79386f0-97bb-11e9-aaa4-230d5a50062d