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>
diff --git a/internal/lsp/cache/view.go b/internal/lsp/cache/view.go
index 90393c8..80560f1 100644
--- a/internal/lsp/cache/view.go
+++ b/internal/lsp/cache/view.go
@@ -119,6 +119,10 @@
 		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