Change few testcase descriptions

Reaction to changes in 130cbcfaa3.

spec/unit/compiler/passes/report-infinite-loops.spec.js

@@ -25,7 +25,7 @@ describe("compiler pass |reportInfiniteLoops|", function() {
     });
   });
 
-  it("computes empty string matching correctly", function() {
+  it("computes expressions that always advance on success correctly", function() {
     expect(pass).toReportError([
       'start = a*',
       'a "a" = ""'

spec/unit/compiler/passes/report-left-recursion.spec.js

@@ -39,7 +39,7 @@ describe("compiler pass |reportLeftRecursion|", function() {
       expect(pass).not.toReportError('start = "" "" "a" start');
     });
 
-    it("computes empty string matching correctly", function() {
+    it("computes expressions that always advance on success correctly", function() {
       expect(pass).toReportError([
         'start = a start',
         'a "a" = ""'