Change Fasta testing docs to use 32-bit when possible.

pkg/front_end/lib/src/fasta/TESTING.md

Index: pkg/front_end/lib/src/fasta/TESTING.md
diff --git a/pkg/front_end/lib/src/fasta/TESTING.md b/pkg/front_end/lib/src/fasta/TESTING.md
index c8665abb742cc03142d2528ae765dd16ca04b99c..570c8e08c25984dfe5b0556beb4ee764d0285408 100644
--- a/pkg/front_end/lib/src/fasta/TESTING.md
+++ b/pkg/front_end/lib/src/fasta/TESTING.md
@@ -8,6 +8,8 @@ BSD-style license that can be found in the LICENSE file.
 When changing Fasta, your changes can affect dart2js or the VM, so you may need
 to test them.
 
+Most of the tests below use a 32-bit build because the test runs significantly faster.

[ahe, 2017/03/15 14:58:51]

Should we include the command line for building? I use:

./tools/build.py --mode release --arch x64,ia32 runtime_kernel
dart_precompiled_runtime

We need to build remember to build before running -cdartk tests, as we otherwise
will be running the previously built version of Fasta.

[Paul Berry, 2017/03/15 17:24:09]

I actually think we're ok with what we've got.  For the test commands on lines
20, 29, and 32, it's not necessary to do a build.  For the test command on line
43, a build is necessary, but the command on line 43 takes care of it (note that
it says `./tools/build.py ... && ...`).

If you want to propose a CL that spells this out in more detail I'm open to it,
though.

[ahe, 2017/03/16 08:39:27]

Good point.

+
 <!-- TODO(ahe): Soon, also the analyzer. -->
 
 ## Test package:front_end and package:analyzer.
@@ -15,7 +17,7 @@ to test them.
 The absolutely bare minimum of testing is the basic unit tests:
 
 ```
-./tools/test.py -mrelease 'pkg/front_end|*fasta*' --checked --time -pcolor --report --failure-summary
+./tools/test.py -mrelease 'pkg/front_end|*fasta*' --checked --time -pcolor --report --failure-summary -aia32
 ```
 
 ## Testing dart2js
@@ -24,16 +26,18 @@ If you're making changes to dart2js, it most likely involves the scanner or pars
 
 ```
 # Unit tests for dart2js
-./tools/test.py --dart2js-batch --time -pcolor --report --failure-summary -ax64 -mrelease --checked dart2js
+./tools/test.py --dart2js-batch --time -pcolor --report --failure-summary -aia32 -mrelease --checked dart2js
 
 # Language and co19, dart2js.
-./tools/test.py --dart2js-batch --time -pcolor --report --failure-summary -ax64 -mrelease -cdart2js -rd8 language co19
+./tools/test.py --dart2js-batch --time -pcolor --report --failure-summary -aia32 -mrelease -cdart2js -rd8 language co19
 ```
 
 ## Testing the Dart VM
 
 If you're making changes that affect Kernel output, for example, BodyBuilder.dart, you probably also need to test on the VM:
 
+Note that this test requires a 64-bit build because app-jit snapshot does not work for ia32.
+
 ```
 # Language, co19, kernel, for VM using Fasta.
 ./tools/build.py -mrelease runtime_kernel && ./tools/test.py -mrelease -cdartk co19 language kernel --time -pcolor --report --failure-summary -j16