Add more StringToDouble test cases

Some callers (in bigger, more complicated code and tests) rely on
StringToDouble's "return non-zero with failure" best-effort behavior
when the number has a unit suffix.

Change-Id: I7ac38fec189e8193895547664ddc09c071e1bdc4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2310370
Commit-Queue: Nigel Tao <nigeltao@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791381}

base/strings/string_number_conversions_unittest.cc

@@ -841,6 +841,8 @@ TEST(StringNumberConversionsTest, StringToDouble) {
       {"+123 e4", 123.0, false},
       {"123e ", 123.0, false},
       {"123e", 123.0, false},
+      {"10.5px", 10.5, false},
+      {"11.5e2em", 1150, false},
       {" 2.99", 2.99, false},
       {"1e3.4", 1000.0, false},
       {"nothing", 0.0, false},