Don't add unnecessary quotes to the rhs of the descendant operator. bug 321547, r=brendan

js/src/jsemit.c

@@ -2262,6 +2262,11 @@ EmitElemOp(JSContext *cx, JSParseNode *pn, JSOp op, JSCodeGenerator *cg)
         if (!js_EmitTree(cx, cg, left))
             return JS_FALSE;
     }
+    /* The right side of the descendant operator is implicitly quoted. */
+    if (op == JSOP_DESCENDANTS && right->pn_op == JSOP_STRING &&
+        js_NewSrcNote(cx, cg, SRC_UNQUOTE) < 0) {
+        return JS_FALSE;
+    }
     if (!js_EmitTree(cx, cg, right))
         return JS_FALSE;
     if (js_NewSrcNote2(cx, cg, SRC_PCBASE, CG_OFFSET(cg) - top) < 0)
@@ -4953,7 +4958,7 @@ JS_FRIEND_DATA(JSSrcNoteSpec) js_SrcNoteSpec[] = {
     {"pcdelta",         1,      0,      1},
     {"assignop",        0,      0,      0},
     {"cond",            1,      0,      1},
-    {"reserved0",       0,      0,      0},
+    {"unquote",         0,      0,      0},
     {"hidden",          0,      0,      0},
     {"pcbase",          1,      0,     -1},
     {"label",           1,      0,      0},

js/src/jsemit.h

@@ -415,7 +415,7 @@ typedef enum JSSrcNoteType {
                                    gets and sets */
     SRC_ASSIGNOP    = 8,        /* += or another assign-op follows */
     SRC_COND        = 9,        /* JSOP_IFEQ is from conditional ?: operator */
-    SRC_RESERVED0   = 10,       /* reserved for future use */
+    SRC_UNQUOTE     = 10,       /* don't quote a JSOP_STRING */
     SRC_HIDDEN      = 11,       /* opcode shouldn't be decompiled */
     SRC_PCBASE      = 12,       /* distance back from annotated get- or setprop
                                    op to first obj.prop.subprop bytecode */

js/src/jsopcode.c

@@ -2128,8 +2128,11 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
               END_LITOPX_CASE
 
               BEGIN_LITOPX_CASE(JSOP_STRING)
+                sn = js_GetSrcNote(jp->script, pc);
                 rval = QuoteString(&ss->sprinter, ATOM_TO_STRING(atom),
-                                   (jschar)(inXML ? 0 : '"'));
+                                   (jschar)((inXML ||
+                                             (sn && SN_TYPE(sn) == SRC_UNQUOTE))
+                                            ? 0 : '"'));
                 if (!rval)
                     return JS_FALSE;
                 todo = STR2OFF(&ss->sprinter, rval);