exp/eval test: fix build

R=r
CC=golang-dev
https://golang.org/cl/1599043

src/pkg/exp/eval/expr_test.go

@@ -12,7 +12,7 @@ import (
 var undefined = "undefined"
 var typeAsExpr = "type .* used as expression"
 var badCharLit = "character literal"
-var illegalEscape = "illegal char escape"
+var unknownEscape = "unknown escape sequence"
 var opTypes = "illegal (operand|argument) type|cannot index into"
 var badAddrOf = "cannot take the address"
 var constantTruncated = "constant [^ ]* truncated"
@@ -37,7 +37,7 @@ var exprTests = []test{
 	// Produces two parse errors
 	//CErr("'''", ""),
 	CErr("'\n'", badCharLit),
-	CErr("'\\z'", illegalEscape),
+	CErr("'\\z'", unknownEscape),
 	CErr("'ab'", badCharLit),
 
 	Val("1.0", bignum.Rat(1, 1)),
@@ -48,7 +48,7 @@ var exprTests = []test{
 	Val("\"abc\"", "abc"),
 	Val("\"\"", ""),
 	Val("\"\\n\\\"\"", "\n\""),
-	CErr("\"\\z\"", illegalEscape),
+	CErr("\"\\z\"", unknownEscape),
 	CErr("\"abc", "string not terminated"),
 
 	Val("(i)", 1),