Adjust stringContentTDQ, stringContentTSQ to allow escapes.

Bug: 33090.
Change-Id: Id8c0d26a4f4072a97cc71c8f3f05f0694c304491
Reviewed-on: https://dart-review.googlesource.com/61923
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
diff --git a/docs/language/dartLangSpec.tex b/docs/language/dartLangSpec.tex
index fafc0c0..bad2ba0 100644
--- a/docs/language/dartLangSpec.tex
+++ b/docs/language/dartLangSpec.tex
@@ -3989,10 +3989,12 @@
   .
 
 {\bf stringContentTDQ:}\~{}( `$\backslash$' $|$ `{\escapegrammar \texttt{"""}}' $|$ `\$');
+  `$\backslash$' \~{}( NEWLINE );
   stringInterpolation
   .
 
 {\bf stringContentTSQ:}\~{}( `$\backslash$' $|$ `{\escapegrammar \code{'}\code{'}\code{'}}' $|$ `\$');
+  `$\backslash$' \~{}( NEWLINE );
   stringInterpolation
   .