plots: make autosize dflt *true* on layouts with no set width / height

... for backward compatibly, in particular
    https://plot.ly/javascript/responsive-fluid-layout/

- reset patched modebar, and resize test to original.

Author: etpinard

src/plots/plots.js

@@ -896,7 +896,17 @@ plots.supplyLayoutGlobalDefaults = function(layoutIn, layoutOut) {
         color: globalFont.color
     });
 
-    coerce('autosize');
+    // Make sure that autosize is defaulted to *true*
+    // on layouts with no set width and height for backward compatibly,
+    // in particular https://plot.ly/javascript/responsive-fluid-layout/
+    //
+    // Before https://github.com/plotly/plotly.js/pull/635 ,
+    // layouts with no set width and height were set temporary set to 'initial'
+    // to pass through the autosize routine
+    //
+    // This behavior is subject to change in v2.
+    coerce('autosize', !(layoutIn.width && layoutIn.height));
+
     coerce('width');
     coerce('height');
     coerce('margin.l');

test/jasmine/tests/modebar_test.js

@@ -643,7 +643,6 @@ describe('ModeBar', function() {
                 }];
 
                 var mockLayout = {
-                    autosize: true,
                     xaxis: {
                         anchor: 'y',
                         domain: [0, 0.5],

test/jasmine/tests/plots_test.js

@@ -304,7 +304,7 @@ describe('Test Plots', function() {
         beforeAll(function(done) {
             gd = createGraphDiv();
 
-            Plotly.plot(gd, [{ x: [1, 2, 3], y: [2, 3, 4] }], { autosize: true })
+            Plotly.plot(gd, [{ x: [1, 2, 3], y: [2, 3, 4] }])
                 .then(function() {
                     gd.style.width = '400px';
                     gd.style.height = '400px';