internal/lsp: fix crash caused by lack of TypeSizes from go/packages.Load

Get dummy sizes values until we can get go/packages to forward the correct
values.

Change-Id: Ie31333e9ed7c57d02e1447097567fa894ea9de7d
Reviewed-on: https://go-review.googlesource.com/c/161937
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/cache/view.go

@@ -119,6 +119,10 @@ func (v *View) parse(uri source.URI) error {
 		if err := imp.addImports(pkg); err != nil {
 			return err
 		}
+
+		// TODO(rstambler): Get real TypeSizes from go/packages.
+		pkg.TypesSizes = &types.StdSizes{}
+
 		imp.importPackage(pkg.PkgPath)
 	}
 	return nil