Fix number format tests

[asheemmamoowala]

Closes #8537

Fixes two number-format expression tests errors and adds test-expressions to the test-suite script.

number-format/currency

In node v10, ICU was updated in a way that changed behavior of Intl.NumberFormat. To fix the discrepancy in output from Intl.NumberFormat , switch to using a supported locale en-US instead of specifying ja-JP/de-DE, which are not supported locales in default installations of node (with small-icu)

number-format/precision

The expression tests stripped decimal precision when testing number type values in deepEqual.

mapbox-gl-js/test/integration/lib/expression.js

Lines 52 to 57 in a36fc99

	function deepEqual(a, b) {
	if (typeof a !== typeof b)
	return false;
	if (typeof a === 'number') {
	return stripPrecision(a) === stripPrecision(b);
	}

This test is comparing string-ified number values, which does not strip precision. Since the test is validating that trailing 0s are added, I reduced the precision of the input number so that rounding differences in Intl.NumberFormat between node versions does not alter the test expectations.

• briefly describe the changes in this PR
• write tests for all new functionality
• document any changes to public APIs
• post benchmark scores
• manually test the debug page
• tagged @mapbox/studio and/or @mapbox/maps-design if this PR includes style spec changes
• tagged @mapbox/gl-native if this PR includes shader changes or needs a native port